Computer History Wiki - User contributions [en]

VT50

2026-10-07T10:53:38Z

Jnc: Redir - covered there

#Redirect [[VT52]]

DEC manuals

2026-10-07T10:51:09Z

Jnc: /* Identification/numbering system */ +PG - 'Pocket Service Guide'

'''DEC manuals''' were accumulated by [[Digital Equipment Corporation|DEC]] over several decades. Dating, as it did, from the early days of the industry, and originally catering primarily to engineers, who were able to repair and modify their DEC machines, it always had the habit of making available extensive documentation on its machines.

Many have now been scanned, and are available on/through the Internet; this is a huge benefit to the museums and many collectors who now keep, maintain and run collectable DEC gear.

==Identification/numbering system==

Similar to [[DEC engineering drawing numbers]], DEC manuals all had an identification 'number' (it included letters). There were two different systems: one in use up to about April, 1975; the other, thereafter.

In the first, they had the form 'DEC-ww-xxxxxx-y-z'; 'ww' was a number which indicated which [[List of Programmed Data Processors|line]] the manual was for/associated-with (e.g. "10" for the [[PDP-10]], "11" for [[PDP-11]]'s). The rest were all letters; 'z' indicated the revision level of that particular manual, so the first one had an 'A'.

In the second, they had the form 'ww-xxxx-yy-zzz'. 'ww' was an alphabetic code (similar to [[DEC engineering drawing numbers#Drawing codes|DECdrawing codes]]), which indicated what class of document it was. The following codes are known:

* AA - Software documentation
* AD - Addenda
* AE - [[Software Product Description]]
* AV - Reference cards
* DS - [[DEC Alpha|Alpha]] CPU/Chipset documentation
* EB - Books, including Handbooks
* EC - Alpha system component documentation
* EK - Hardware Documentation
* EY - Educational Services

The next field, 'xxxx', indicated which type of system/module the manual was for. 'yy' indicated the type of manual it was; the following typs (again, similar to drawing codes) are known:

* MM - 'Maintenance Manual'
* OP - 'Operator's Manual'
* PG - 'Pocket Service Guide'
* TM - 'Technical Manual'
* UG - 'User Guide'

The 'zzz' was a number indicating the revision level of the manual at hand; it started at '001'.

==Online collections==

There are several large collections online, on/through the Internet (see links below).

Manx, in addition to indexing many online collections, once hosted copies of several collections (notably Antonio Carlini's large collection). These appear to have been removed (the reason is unknown); confusingly, Manx's database ''still contains'' links to copies of things once hosted at Manx, but the files themselves are no longer accessible. Some of the removed files are still accessible through the Internet Archive (see links below), if you have the old Manx URL. Many appear to also be available through VT100.net, but no general index to them there appears to be available; although, oddly enough, some search engines appear to know of them - perhaps because Manx itself still/now links to them!

==See also==

* [[DEC engineering drawing numbers]]
* [[:Category:DEC Documentation|DEC Documentation]]
* [[DEC Unique Product Identifier]]

==External links==

* [https://web.archive.org/web/20250529050040/https://manx-docs.org/collections/antonio/dec/standards/el-00012-01-0000.pdf DEC STD 012-1 Documentation Identification Conventions Including Mnemonic Codes] - still later specification
* [http://www.bitsavers.org/pdf/dec/ DEC] - the primary online collection is at [[Bitsavers]]
** [http://www.bitsavers.org/pdf/dec/catalog/MaintenancePrintPNs.txt Maintenance Print list]
* [https://manx-docs.org/ Manx] - Manx indexes many online collections of manuals
** [https://manx-docs.org/about.php About Manx]
** [https://web.archive.org/web/20250606230756/https://manx-docs.org/collections/antonio/dec/ Antonio] - Manx's copy of Antonio Carlini's collection, in the Internet Archive
** [https://web.archive.org/web/20250606230809/https://manx-docs.org/collections/hcps/ HCPS] - Manx's copy of the HCPS collection, in the Internet Archive
* [https://vaxhaven.com/Documentation Documentation] - VAXHaven
* [https://wwcm.synology.me/scanned.html Main Scanned Document List] - at Wilber Williams' Computer Museum
* [https://www.mainecoon.com/classiccmp/ classiccmp] - Chris Kennedy's archive of Henk Gooijen's scans
* [https://vt100.net/ VT100.net]
* [http://chiappa.net/~jnc/tech/FMPSOnline.html 'Missing' Digital Equipment Corporation Field Maintenance Print Sets Online]

[[Category: Digital Equipment Corporation]]
[[Category: DEC Documentation]]
[[Category: DEC Naming/Numbering Schemes]]

VT52

2026-10-07T10:49:31Z

Jnc: Separate VT50

The '''VT52''' was a very popular [[video terminal]] by [[Digital Equipment Corporation|DEC]], introduced in 1975. The [[cathode ray tube|CRT]] displayed 24 lines of 80 characters in both upper and lower case.

[[Image:vt52.jpg|thumb|right|VT52 terminal]]

It used a custom processor built from [[transistor-transistor logic|TTL]] parts to execute 1024 words of 8-bit wide [[microcode]]. The [[data path]] was 7 bits wide, as was the 2048-word [[Random Access Memory|RAM]].

The predecessor '''VT50''' was almost identical, except there was only 512 words of microcode, 1024 words of RAM, the CRT display 12 lines, and text was upper case only.

A VT52-compatible terminal emulator was used in the [[Atari]] [[Atari TOS|TOS]] [[operating system]].

==Escape sequences==

Due to its popularity, the VT52 escape sequences became a de facto standard for microcomputers for a while, before VT100 and ANSI took over.

{| class="wikitable"
! Name || Sequence || Description
|-
| Line Feed || LF || Move cursor down. On last line, scroll text up.
|-
| Cursor Down || ESC B || Move cursor down. On last line, do not scroll.
|-
| Reverse Line Feed || ESC I || Move cursor up. On first line, scroll text down.
|-
| Cursor Up || ESC A || Move cursor up. On first line, do not scroll.
|-
| Cursor Right || ESC C || Move cursor right. On last column, stay there.
|-
| Cursor Left || ESC D, or BS || Move cursor left. On first column, stay there.
|-
| Home || ESC H || Move cursor to top line, first column.
|-
| Carriage Return || CR || More cursor to first column.
|-
| || TAB || Move cursor to next tab stop.
|-
| Direct Cursor Addressing || ESC Y <line> <column> || Move cursor.
|-
| Erase to End of Line || ESC K || Erase from cursor position to end of line.
|-
| Erase to End of of Screen || ESC J || Erase from cursor position to end of screen.
|-
| Ring the Bell || BEL || Sound the buzzer
|-
| Identify Terminal Type || ESC Z || Respond e.g. "ESC K" for a plain VT52.
|-
| Enter Hold Screen Mode || ESC [ ||
|-
| Exit Hold Screen Mode || ESC \ ||
|-
| Enter Alternate Keypad Mode || ESC = ||
|-
| Exit Alternate Keypad Mode || ESC > ||
|-
| Enter Graphics Mode || ESC F ||
|-
| Exit Graphics Mode || ESC G ||
|-
| colspan="3" | Extensions from Digital Research
|-
| Erase and Home || ESC E || Erase screen and move cursor to top line, first column.
|-
| Erase Current Line || ESC l ||
|-
| Erase to Beginning of Line || ESC o ||
|-
| Erase to Beginning of Screen || ESC d ||
|-
| Insert Line || ESC L ||
|-
| Save Cursor Position || ESC j
|-
| Restore Cursor Position || ESC k ||
|-
| Reverse Video || ESC p ||
|-
| Normal Video || ESC q ||
|-
| Set Foreground Color || ESC b <color> ||
|-
| Set Background Color || ESC c <color> ||
|-
| Enable Cursor || ESC e ||
|-
| Disable Cursor || ESC d ||
|-
| Enable Line Wrap || ESC v ||
|-
| Disable Line Wrap || ESC w ||
|}

{{semi-stub}}

==External links==

* [http://www.bitsavers.org/pdf/dec/terminal/vt52/ VT52] - documentation at [[Bitsavers]]
** [http://www.bitsavers.org/pdf/dec/terminal/vt52/EK-VT5X-OP-001_DECscope_Users_Manual_Mar77.pdf DECscope Users' Manual] (EK-VT5X-OP-001)
** [http://www.bitsavers.org/pdf/dec/terminal/vt52/EK-VT52-MM-002_maint_Jul78.pdf VT52 DECscope Maintenance Manual] (EK-VT52-MM-002)
** [http://www.bitsavers.org/pdf/dec/terminal/vt52/MP00035_VT52schem.pdf VT52 Field Maintenance Print Set] (MP00035)
* [https://vt100.net/dec/ek-vt502-pg-001.pdf VT50/VT52 Pocket Service Guide] (EK-VT502-PG-001)
* [https://github.com/larsbrinkhoff/vt52-simulator/tree/master/rom Microcode ROM images]
* [https://github.com/fritzm/vt52/tree/master/data Character generator ROM image]
* [https://github.com/larsbrinkhoff/terminal-simulator/tree/master/vt52 VT52 hardware simulation]

{{Nav DEC Terminals}}

[[Category: DEC Video Terminals]]

VT52

2026-10-07T10:48:19Z

Jnc: /* External links */ +VT50/VT52 Pocket Service Guide

The '''VT52''' was a very popular [[video terminal]] by [[Digital Equipment Corporation|DEC]], introduced in 1975. The [[cathode ray tube|CRT]] displayed 24 lines of 80 characters in both upper and lower case.

[[Image:vt52.jpg|thumb|right|VT52 terminal]]

It used a custom processor built from [[transistor-transistor logic|TTL]] parts to execute 1024 words of 8-bit wide [[microcode]]. The [[data path]] was 7 bits wide, as was the 2048-word [[Random Access Memory|RAM]]. The predecessor VT50 was almost identical, except there was only 512 words of microcode, 1024 words of RAM, the CRT display 12 lines, and text was upper case only.

A VT52-compatible terminal emulator was used in the [[Atari]] [[Atari TOS|TOS]] [[operating system]].

==Escape sequences==

Due to its popularity, the VT52 escape sequences became a de facto standard for microcomputers for a while, before VT100 and ANSI took over.

{| class="wikitable"
! Name || Sequence || Description
|-
| Line Feed || LF || Move cursor down. On last line, scroll text up.
|-
| Cursor Down || ESC B || Move cursor down. On last line, do not scroll.
|-
| Reverse Line Feed || ESC I || Move cursor up. On first line, scroll text down.
|-
| Cursor Up || ESC A || Move cursor up. On first line, do not scroll.
|-
| Cursor Right || ESC C || Move cursor right. On last column, stay there.
|-
| Cursor Left || ESC D, or BS || Move cursor left. On first column, stay there.
|-
| Home || ESC H || Move cursor to top line, first column.
|-
| Carriage Return || CR || More cursor to first column.
|-
| || TAB || Move cursor to next tab stop.
|-
| Direct Cursor Addressing || ESC Y <line> <column> || Move cursor.
|-
| Erase to End of Line || ESC K || Erase from cursor position to end of line.
|-
| Erase to End of of Screen || ESC J || Erase from cursor position to end of screen.
|-
| Ring the Bell || BEL || Sound the buzzer
|-
| Identify Terminal Type || ESC Z || Respond e.g. "ESC K" for a plain VT52.
|-
| Enter Hold Screen Mode || ESC [ ||
|-
| Exit Hold Screen Mode || ESC \ ||
|-
| Enter Alternate Keypad Mode || ESC = ||
|-
| Exit Alternate Keypad Mode || ESC > ||
|-
| Enter Graphics Mode || ESC F ||
|-
| Exit Graphics Mode || ESC G ||
|-
| colspan="3" | Extensions from Digital Research
|-
| Erase and Home || ESC E || Erase screen and move cursor to top line, first column.
|-
| Erase Current Line || ESC l ||
|-
| Erase to Beginning of Line || ESC o ||
|-
| Erase to Beginning of Screen || ESC d ||
|-
| Insert Line || ESC L ||
|-
| Save Cursor Position || ESC j
|-
| Restore Cursor Position || ESC k ||
|-
| Reverse Video || ESC p ||
|-
| Normal Video || ESC q ||
|-
| Set Foreground Color || ESC b <color> ||
|-
| Set Background Color || ESC c <color> ||
|-
| Enable Cursor || ESC e ||
|-
| Disable Cursor || ESC d ||
|-
| Enable Line Wrap || ESC v ||
|-
| Disable Line Wrap || ESC w ||
|}

{{semi-stub}}

==External links==

* [http://www.bitsavers.org/pdf/dec/terminal/vt52/ VT52] - documentation at [[Bitsavers]]
** [http://www.bitsavers.org/pdf/dec/terminal/vt52/EK-VT5X-OP-001_DECscope_Users_Manual_Mar77.pdf DECscope Users' Manual] (EK-VT5X-OP-001)
** [http://www.bitsavers.org/pdf/dec/terminal/vt52/EK-VT52-MM-002_maint_Jul78.pdf VT52 DECscope Maintenance Manual] (EK-VT52-MM-002)
** [http://www.bitsavers.org/pdf/dec/terminal/vt52/MP00035_VT52schem.pdf VT52 Field Maintenance Print Set] (MP00035)
* [https://vt100.net/dec/ek-vt502-pg-001.pdf VT50/VT52 Pocket Service Guide] (EK-VT502-PG-001)
* [https://github.com/larsbrinkhoff/vt52-simulator/tree/master/rom Microcode ROM images]
* [https://github.com/fritzm/vt52/tree/master/data Character generator ROM image]
* [https://github.com/larsbrinkhoff/terminal-simulator/tree/master/vt52 VT52 hardware simulation]

{{Nav DEC Terminals}}

[[Category: DEC Video Terminals]]

VT05 Alphanumeric Display Terminal

2026-10-07T10:38:29Z

Jnc: /* External links */ Reduce number of external sites relied on

[[Image:VT05.jpg|300px|thumb|right|Marketing photo of VT05 terminal (the image in the screen is apparently manipulated; the monitor was white monochrome)]]

The '''VT05 Alphanumeric Display Terminal''' (technically, the '''VT05B''', but documentation usually referred to it as the 'VT05') was one of [[Digital Equipment Corporation|DEC]]'s first [[video terminal]]s. It supported all the same format control characters as a [[Teletype]], so it was a 'drop in' replacement.

Physically, it was 12"Hx19"Wx30"D, and weighed 55lbs. Its circuitry was contained on seven modules to aid maintenance.

The display was 10-1/8"x7-5/8", and could hold 72Wx20H characters, using a 5x7 [[font]], producing characters .22"x.10", upper-case only. (It could send lower- and upper-case from the keyboard, however.) It also supported addressable screen output, using a [[cursor]] which could be placed anywhere on the screen, with output being placed at the cursor location.

Its [[asynchronous serial line]] interface supported both [[EIA RS-232 serial line interface|RS-232]] and [[20mA current loop serial line interface|20mA]] at [[baud rate]]s of 110 to 2400 baud, including several split speed combinations (e.g. 110 out and 2400 in). It could operated in both [[half-duplex]] and [[full-duplex]] modes.

It could also accept video input, and display that alongside text; video output was also produced.

==External links==

* [https://vt100.net/docs/vt05-rm/ VT05 alphanumeric display terminal reference manual] (DEC-00-H4AC-D)
* [https://vt100.net/dec/dec-00-h4bd-d-vt05-maintenance-manual.pdf VT05 alphanumeric display terminal maintenance manual] (DEC-00-H4BD-D)
* [http://www.bitsavers.org/pdf/dec/terminal/vt05/DEC-VT05-IPB-1.pdf VT05 alphanumeric display terminal Illustrated Parts Breakdown] (DEC-VT05-IPB-1)
* [http://www.bitsavers.org/pdf/dec/terminal/vt05/VT05_Engineering_Drawings_Jun71.pdf VT05 alphanumeric display terminal engineering drawings]

{{Nav DEC Terminals}}

[[Category: DEC Video Terminals]]

KL10

2026-10-07T07:30:14Z

Jnc: /* External Links */ KL10 Backplane image

{{Infobox Machine
| name = KL10
| manufacturer = [[Digital Equipment Corporation]]
| architecture = [[PDP-10]]
| year design started = January, 1972
| year first shipped = June, 1975
| form factor = [[mainframe]]
| word size = 36 bits
| physical address = 22 bits
| virtual address = 18 bits (Model A)<br>23 bits (Model B)
| logic type = [[emitter-coupled logic|ECL]] [[IC]]s
| design type = clocked synchronous, [[microcode]]d
| uword width = 75 (Model A)<br>76 (Model B)
| ucode length = 1280 (Model A)<br>2K (Model B)
| clock speed = 50 MHz (Model A)<br>58 MHz (Model B)
| cache size = 2K words (KL10-PA and PV)<br>4K words (KL10-PW)
| memory speed = 1.0 μsec (initial [[core memory]]), 500 nsec (later [[Metal Oxide Semiconductor|MOS]] [[main memory]])
| memory mgmt = [[paging]], 512-word pages
| operating system = [[TOPS-10]], [[TOPS-20]], [[Incompatible Timesharing System|ITS]], [[WAITS]], [[TENEX]], [[TYMCOM-X]]
| predecessor = [[KI10]]
| successor = none
| price = US$250K (CPU), US$600K-1.2M (system)
}}

The '''KL10''' was the third generation of [[PDP-10]] processors. It was built out of [[Emitter-coupled logic|ECL]], on [[DEC card form factor|hex]] cards. It was the first [[microcode|micro-programmed]] PDP-10 processor; the design was inspired by Stanford's [[Super Foonly]].

The [[Central Processing Unit|CPU]] had two main units, the 'E Box' ('Execution') and the 'M Box' ('Memory'). It provided three types of [[bus]]ses to the rest of the components of the system; the 'E Bus', from the E Box; and the 'S Bus' ('Storage'), and later the 'C Bus' ('[[Channel]]'), from the M Box. The S Bus (usually called the 'internal' memory bus) was for the attachment of [[main memory]] units, while the C Bus allowed [[Direct Memory Access|DMA]] accesss to main memory.

(The S Bus was later modififed to a version called the 'X Bus', which was functionally the same as the S Bus, but used [[transistor-transistor logic|TTL]] [[signal]] [[voltage]]s, instead of the [[emitter-coupled logic|ECL]] levels of the S Bus.)

A KL10 could support up to 4 [[DTE20 Ten-Eleven Interface‎‎]]s; they allowed connection of a [[PDP-11]] [[front end]]. At least one PDP-11, the 'master', was ''required''; it could [[bootstrap]] the KL10, including loading the [[microcode]].

A main memory [[cache]] for [[instruction]] and [[operand]] [[fetch]]es, the [[MCA20 Cache]] - standard in some models, and optional in others - was available. Later in the KL10's life, the improved [[MCA25 KL Cache/Paging Upgrade]], which increased both the size of both the main memory cache, and the [[virtual memory|paging]] cache, as well as improved the functionality of the latter, could be added/substituted for the MCA20.

A [[DMA20 Memory Bus Adapter]] could be attached to the S Bus, to provide up to 4 (in parallel, to increase memory bandwidth, as well as maximizing [[memory interleaving]]) [[KI10]]-compatible [[PDP-10 Memory Bus|external memory busses]] (called the 'K Bus' in the KL10). Similarly, an [[DIA20 In/Out Bus Controller]] could be attached to the E Bus, to provide a [[PDP-10 I/O Bus]] (called the I Bus in the KL10).

The KL10 was used in the [[DECsystem-10]] models 108x and 109x systems (initially with an external memory bus and an I/O bus, as a 'drop-in' processor replacement for a KI10), and in the high-end 20xx systems of the [[DECSYSTEM-20]] line (with an internal memory bus).

Like its predecessor, the KI10, it was initially released in a single-processor version; a [[multi-processor]] version was released later (although only [[TOPS-10]] ever supported it).

==Devices==

Up to 8 [[RH20 MASSBUS controller]]s could be installed; they connect to the E Bus (for control), and also to the C Bus (for data movement). The [[MASSBUS]] can be used to connect a variety of [[disk]] and [[magnetic tape]] [[mass storage]] devices.

Two optional high-speed [[data network]]ing [[peripheral]]s are also available:

* [[NIA20 Network Interconnect Adapter]] - an [[Ethernet]] interface
* [[CI20 Computer Interconnect]] - interface to the [[Computer Interconnect|CI]] high-speed link

If either the NIA2O or CI20 in installed, since they use some of the [[backplane]] slots for the RH20's, only 4 RH20's may be installed if either is installed. They also connect to the EBUS and CBUS.

All low-speed devices were generally attached to the [[UNIBUS]] of one of the PDP-11 front ends (which could also be attached via a [[DL10 PDP-11 Data Link|DL10]]); although the I Bus provided by a DIA20 was also an option.

==Construction==

There were two main packaging families: those used for the DECsystem-10, which used tall, medium-width cabinets like those of the KA10 and KI10, in the same turquoise blue as the latter; and the DECSYSTEM-20, which were shorter and wider and painted cream and orange.

The CPU, front end, and I/O controllers were accommodated in a set of three racks (or four, for some DECSYSTEM-20s); one to hold the CPU, one for the front-end, and one for all the I/O. The E Box and the M Box were both on the main backplane, in the CPU cabinet. The DMA20, DIA20, DTE20s and RH20s were all accommodated on backplanes in the second, I/O, cabinet; the first two were on a single backplane, and the latter two on another.

==Versions==

There were a number of variants over the lifetime of the KL10; the situation is confusing because there appear to be three different, somewhat orthogonal, [[namespace]]s for KL10 variants:

* CPU hardware variants (-PA, -PV and -PW);
* informal internal names for CPU variations ('Model A', 'Model B');
* KL10 'models' (-A through -E, and -R).

As far as is known, 'Model A' is an internal aphorism for -PA, and
'Model B' for -PV; the two are described in a DEC document as:

* "KL10-PA - A basic ECL processor with slots for cache and internal channels. Unofficially .. referred to as the Model A machine."
* "KL10-PV - A KL10-PA which has been modified to include extended addressing, more extensive microcode, and a faster [[clock]]. Unofficially .. referred to as the Model B machine."

The KL10-PV supported the 'Extended' PDP-10 [[architecture]], with support for multiple 'sections' (256K-[[word]] [[address space]]s), available to both the [[kernel]] and the [[user]] (although apparently only [[TOPS-20]] supported the latter). The earlier machines could be field upgraded to a -PV, but it apparently needed a modified/new backplane.

Substitution/addition of the later MCA25 cache produced the KL10-PW; the resulting machine was named the 'Model C' by some.

Many of the 'models' (e.g. 'KL10-C' and 'KL10-D') appear to be names for particular configurations (with various options, such as the DMA20 and DIA20); here is a DEC table which (hopefully authoritatively) defines them:

{| class="wikitable"
! Model !! PV !! Cache !! Int Chans !! Max DTEs !! Max RH20s !! DIA !! DMA
|-
| KL10-A || No || Yes || No || 1 || 0 || Yes || Yes
|-
| KL10-B || No || Yes || Yes || 4 || 8 || Yes || Yes
|-
| KL10-C || No || Optional || Yes || 4 || 8 || No || No
|-
| KL10-D || Yes || Yes || Yes || 4 || 8* || Yes || Yes
|-
| KL10-E || Yes || Optional || Yes || 4 || 8* || Optional || Optional
|-
| KL10-R || Yes || Optional || Yes || 4 || 8* || Optional || Optional
|}

(*: Maximum 4 RH20s if a CI20 or NIA20 is installed, as those use the slots for RH4-7 in the RH20 backplane.)

The 'KL10-R' appears to be a KL10-E in a new cabinet design, one compliant with newer FCC [[interference|RFI]] emissions standards; but it may also refer to systems with the MCA25.

Note that the early KL10-A only supported a single DTE20, and no RH20s, and it was the later KL10-B and up (the first two also with the Model A CPU), which supported up to 4 DTE20s and up to 8 RH20s. This is because the I/O backplanes in the second bay of the CPU differed in the KL10-B and up, to support the larger I/O configuration. (The DTE20 backplane differed between the two.) The KL10-A was intended to replace KA10 and KI10 processors, hence the lack of support for RH20s, etc.

One significant division between KL-based ''systems'' is between those with an external memory bus (K bus), and those with an internal memory bus (the native S/X Bus).

The DEC numeric model numbers - a fourth namespace - are even more confused, since a 1090 could be either a "KL10-B(PA) or KL10-D(PV)"; similarly, the 2040 and 2050 could be a "KL10-C(PA) or KL10-E(PV)".

==Well-known KL10's==

There was a single KL10 [[Incompatible Timesharing System|ITS]] machine, MIT-MC, a very early Model A. It was later renamed to MX after a [[KS10]] took the 'MC' identity, and was finally shut down in 1988; it is now in storage at the [[Living Computer Museum]].

The [[Stanford Artificial Intelligence Laboratory|SAIL]] (or SU-AI) [[time-sharing]] system — [[WAITS]] — main computer was a KL10 from 1976 to 1991. In 1983, it was upgraded from a model A to a model B CPU. Near the end, failing insulation in the backplane was fixed by inserting toothpicks.

==External Links==

* [http://www.bitsavers.org/pdf/dec/pdp10/KL10/ KL10] - documentation at [[Bitsavers]]
** [http://www.bitsavers.org/pdf/dec/pdp10/KL10/EK-OKL10-TM_KL10_TechRef_Aug84.pdf KL10-Based Technical Manual] (EK-OKL10-TM-002) - good detailed overview
** [http://www.bitsavers.org/pdf/dec/pdp10/KL10/EK-1080U-SD-003_1080_1090_SysDescr_Jan77.pdf decsystem-1080/1090 System Description] (EK-1080U-SD-003) - good medium-level description of the functionality of the KL10 CPU and its peripherals
** [http://www.bitsavers.org/pdf/dec/pdp10/KL10/EK-108OU-PD-002_KL10-Based_Physical_Description_Mar77.pdf KL10-Based Physical Description] (EK-108OU-PD-002) - contains KL10 board configuration, pp. 3-29
** [http://www.bitsavers.org/pdf/dec/pdp10/memos/720829_KL10_Technology_Goals.pdf KL10 Project Technology Goals] - interesting memo discussing the analog aspects of the chip technology used in the KL10
* [https://dodlithr.blogspot.com/2014/04/digitals-decsystem-20-part-5-cpu-kl10.html Digital's DECSYSTEM-20 - Part 5 - CPU (KL10)]
* [http://corestore.org/DEC2065.htm Corestore collection: DECSYSTEM 2065 KL10-RH] - Good images, has two MG20 memory units
* [http://www.shiresoft.com/pdp-11/kl-10/ KL-10]
** [http://www.shiresoft.com/pdp-11/kl-10/io-connectors.jpg KL10 I/O connectors] - Good image of bus connectors: on the bottom, MASSBUS connectors on the left; memory and I/O bus QuickLatch connectors on the right
* [https://wwcm.synology.me/gallery/Pictures/pages/04%20-%20KL10%20Backplane.htm KL10 Backplane] - image of CPU backplane
* [https://www.cca.org/tech/rcs/pdp-11-40/ PDP-11/40] - good images of a KL10 front end
* [http://www.brouhaha.com/~eric/retrocomputing/pdp-10/kl10d_modules.html KL-10D Module Utilization]
* [http://web.archive.org/web/20150919094256/http://www.inwap.com/pdp10/usenet/kl KL] - some interesting discussion of KL10 details
* [http://infolab.stanford.edu/pub/voy/museum/pictures/AIlab/SailFarewell.html SAIL Farewell] - a good thumbnail history
* [https://github.com/PDP-10/its/tree/master/src/ucode KL10 ITS microcode]

[[Category: PDP-10 Processors]]

Video terminal

2026-10-07T07:23:36Z

Jnc: /* External links */ +Archive of Video Terminal Information

A '''video terminal''' (sometimes called '''video display terminal''', or '''VDT''' for short) was a [[terminal]] on which the characters being output were 'painted' on a [[cathode ray tube|CRT]] via a purely [[electronic]] process. It was thus roughly the same functionality as the earlier [[printing terminal]]s, such as [[Teletype]]s, but instead of the output being printed on paper by a mechanical system, it was displayed on the screen. Like the earlier printing terminals, they were used to allow a [[user]] to do [[input/output]] to a computer; they usually communicated with the computer via [[asynchronous serial line]].

The original chief advantage was speed, since the all-electronic mechanism could run at much higher speeds; the disadvantage was that only a limited amount of information could be displayed at one time. (This was particularly true of early ones, which could only display very limited amounts of text - some as small as 12 lines of 40 characters).

Very early model provided only the same motion controls as their printing predecessors - line feed, carriage return, etc. However, the ability to move the [[cursor]] to specific screen locations was soon added, which made possible a predecessor of [[WYSIWYG]], to wit, [[screen editor]]s such as [[Emacs editors|EMACS]].

A few had the capability to do [[graphics]], such as lines, points, etc.

Once [[semiconductor]] [[Random Access Memory|RAM]] prices fell low enough, they were replaced with [[bit-mapped display‏‎]]s, although the latter were directly connected to the computer's main [[bus]], usually on a [[personal computer]].

==See also==

* [[:Category:Video Terminals|Video Terminals]]
* [[flashterm]] - ANSI video terminal emulator

==External links==

* [https://vt100.net/ vt100.net]
** [https://vt100.net/shuford/terminal/ The Archive of Video Terminal Information]
** [https://vt100.net/dec/vt_history Meet the Family] - a brief history of [[Digital Equipment Corporation|DEC]] VDT's
** [https://vt100.net/dec/animation/ DEC Video Terminal Animations]

[[Category: Device Basics‎‎]]

DEC manuals

2026-10-07T07:20:22Z

Jnc: /* External links */ +DEC STD 012-1 Documentation Identification Conventions Including Mnemonic Codes

'''DEC manuals''' were accumulated by [[Digital Equipment Corporation|DEC]] over several decades. Dating, as it did, from the early days of the industry, and originally catering primarily to engineers, who were able to repair and modify their DEC machines, it always had the habit of making available extensive documentation on its machines.

Many have now been scanned, and are available on/through the Internet; this is a huge benefit to the museums and many collectors who now keep, maintain and run collectable DEC gear.

==Identification/numbering system==

Similar to [[DEC engineering drawing numbers]], DEC manuals all had an identification 'number' (it included letters). There were two different systems: one in use up to about April, 1975; the other, thereafter.

In the first, they had the form 'DEC-ww-xxxxxx-y-z'; 'ww' was a number which indicated which [[List of Programmed Data Processors|line]] the manual was for/associated-with (e.g. "10" for the [[PDP-10]], "11" for [[PDP-11]]'s). The rest were all letters; 'z' indicated the revision level of that particular manual, so the first one had an 'A'.

In the second, they had the form 'ww-xxxx-yy-zzz'. 'ww' was an alphabetic code (similar to [[DEC engineering drawing numbers#Drawing codes|DECdrawing codes]]), which indicated what class of document it was. The following codes are known:

* AA - Software documentation
* AD - Addenda
* AE - [[Software Product Description]]
* AV - Reference cards
* DS - [[DEC Alpha|Alpha]] CPU/Chipset documentation
* EB - Books, including Handbooks
* EC - Alpha system component documentation
* EK - Hardware Documentation
* EY - Educational Services

The next field, 'xxxx', indicated which type of system/module the manual was for. 'yy' indicated the type of manual it was; the following typs (again, similar to drawing codes) are known:

* MM - 'Maintenance Manual'
* OP - 'Operator's Manual'
* TM - 'Technical Manual'
* UG - 'User Guide'

The 'zzz' was a number indicating the revision level of the manual at hand; it started at '001'.

==Online collections==

There are several large collections online, on/through the Internet (see links below).

Manx, in addition to indexing many online collections, once hosted copies of several collections (notably Antonio Carlini's large collection). These appear to have been removed (the reason is unknown); confusingly, Manx's database ''still contains'' links to copies of things once hosted at Manx, but the files themselves are no longer accessible. Some of the removed files are still accessible through the Internet Archive (see links below), if you have the old Manx URL. Many appear to also be available through VT100.net, but no general index to them there appears to be available; although, oddly enough, some search engines appear to know of them - perhaps because Manx itself still/now links to them!

==See also==

* [[DEC engineering drawing numbers]]
* [[:Category:DEC Documentation|DEC Documentation]]
* [[DEC Unique Product Identifier]]

==External links==

* [https://web.archive.org/web/20250529050040/https://manx-docs.org/collections/antonio/dec/standards/el-00012-01-0000.pdf DEC STD 012-1 Documentation Identification Conventions Including Mnemonic Codes] - still later specification
* [http://www.bitsavers.org/pdf/dec/ DEC] - the primary online collection is at [[Bitsavers]]
** [http://www.bitsavers.org/pdf/dec/catalog/MaintenancePrintPNs.txt Maintenance Print list]
* [https://manx-docs.org/ Manx] - Manx indexes many online collections of manuals
** [https://manx-docs.org/about.php About Manx]
** [https://web.archive.org/web/20250606230756/https://manx-docs.org/collections/antonio/dec/ Antonio] - Manx's copy of Antonio Carlini's collection, in the Internet Archive
** [https://web.archive.org/web/20250606230809/https://manx-docs.org/collections/hcps/ HCPS] - Manx's copy of the HCPS collection, in the Internet Archive
* [https://vaxhaven.com/Documentation Documentation] - VAXHaven
* [https://wwcm.synology.me/scanned.html Main Scanned Document List] - at Wilber Williams' Computer Museum
* [https://www.mainecoon.com/classiccmp/ classiccmp] - Chris Kennedy's archive of Henk Gooijen's scans
* [https://vt100.net/ VT100.net]
* [http://chiappa.net/~jnc/tech/FMPSOnline.html 'Missing' Digital Equipment Corporation Field Maintenance Print Sets Online]

[[Category: Digital Equipment Corporation]]
[[Category: DEC Documentation]]
[[Category: DEC Naming/Numbering Schemes]]

DEC manuals

2026-10-07T06:47:50Z

Jnc: Add Internet Archive copies of lost collections at Manx

'''DEC manuals''' were accumulated by [[Digital Equipment Corporation|DEC]] over several decades. Dating, as it did, from the early days of the industry, and originally catering primarily to engineers, who were able to repair and modify their DEC machines, it always had the habit of making available extensive documentation on its machines.

Many have now been scanned, and are available on/through the Internet; this is a huge benefit to the museums and many collectors who now keep, maintain and run collectable DEC gear.

==Identification/numbering system==

Similar to [[DEC engineering drawing numbers]], DEC manuals all had an identification 'number' (it included letters). There were two different systems: one in use up to about April, 1975; the other, thereafter.

In the first, they had the form 'DEC-ww-xxxxxx-y-z'; 'ww' was a number which indicated which [[List of Programmed Data Processors|line]] the manual was for/associated-with (e.g. "10" for the [[PDP-10]], "11" for [[PDP-11]]'s). The rest were all letters; 'z' indicated the revision level of that particular manual, so the first one had an 'A'.

In the second, they had the form 'ww-xxxx-yy-zzz'. 'ww' was an alphabetic code (similar to [[DEC engineering drawing numbers#Drawing codes|DECdrawing codes]]), which indicated what class of document it was. The following codes are known:

* AA - Software documentation
* AD - Addenda
* AE - [[Software Product Description]]
* AV - Reference cards
* DS - [[DEC Alpha|Alpha]] CPU/Chipset documentation
* EB - Books, including Handbooks
* EC - Alpha system component documentation
* EK - Hardware Documentation
* EY - Educational Services

The next field, 'xxxx', indicated which type of system/module the manual was for. 'yy' indicated the type of manual it was; the following typs (again, similar to drawing codes) are known:

* MM - 'Maintenance Manual'
* OP - 'Operator's Manual'
* TM - 'Technical Manual'
* UG - 'User Guide'

The 'zzz' was a number indicating the revision level of the manual at hand; it started at '001'.

==Online collections==

There are several large collections online, on/through the Internet (see links below).

Manx, in addition to indexing many online collections, once hosted copies of several collections (notably Antonio Carlini's large collection). These appear to have been removed (the reason is unknown); confusingly, Manx's database ''still contains'' links to copies of things once hosted at Manx, but the files themselves are no longer accessible. Some of the removed files are still accessible through the Internet Archive (see links below), if you have the old Manx URL. Many appear to also be available through VT100.net, but no general index to them there appears to be available; although, oddly enough, some search engines appear to know of them - perhaps because Manx itself still/now links to them!

==See also==

* [[DEC engineering drawing numbers]]
* [[:Category:DEC Documentation|DEC Documentation]]
* [[DEC Unique Product Identifier]]

==External links==

* [http://www.bitsavers.org/pdf/dec/ DEC] - the primary online collection is at [[Bitsavers]]
** [http://www.bitsavers.org/pdf/dec/catalog/MaintenancePrintPNs.txt Maintenance Print list]
* [https://manx-docs.org/ Manx] - Manx indexes many online collections of manuals
** [https://manx-docs.org/about.php About Manx]
** [https://web.archive.org/web/20250606230756/https://manx-docs.org/collections/antonio/dec/ Antonio] - Manx's copy of Antonio Carlini's collection, in the Internet Archive
** [https://web.archive.org/web/20250606230809/https://manx-docs.org/collections/hcps/ HCPS] - Manx's copy of the HCPS collection, in the Internet Archive
* [https://vaxhaven.com/Documentation Documentation] - VAXHaven
* [https://wwcm.synology.me/scanned.html Main Scanned Document List] - at Wilber Williams' Computer Museum
* [https://www.mainecoon.com/classiccmp/ classiccmp] - Chris Kennedy's archive of Henk Gooijen's scans
* [https://vt100.net/ VT100.net]
* [http://chiappa.net/~jnc/tech/FMPSOnline.html 'Missing' Digital Equipment Corporation Field Maintenance Print Sets Online]

[[Category: Digital Equipment Corporation]]
[[Category: DEC Documentation]]
[[Category: DEC Naming/Numbering Schemes]]

DEC manuals

2026-10-07T06:32:41Z

Jnc: /* Online collections */ Manx links to copies at VT100.net

'''DEC manuals''' were accumulated by [[Digital Equipment Corporation|DEC]] over several decades. Dating, as it did, from the early days of the industry, and originally catering primarily to engineers, who were able to repair and modify their DEC machines, it always had the habit of making available extensive documentation on its machines.

Many have now been scanned, and are available on/through the Internet; this is a huge benefit to the museums and many collectors who now keep, maintain and run collectable DEC gear.

==Identification/numbering system==

Similar to [[DEC engineering drawing numbers]], DEC manuals all had an identification 'number' (it included letters). There were two different systems: one in use up to about April, 1975; the other, thereafter.

In the first, they had the form 'DEC-ww-xxxxxx-y-z'; 'ww' was a number which indicated which [[List of Programmed Data Processors|line]] the manual was for/associated-with (e.g. "10" for the [[PDP-10]], "11" for [[PDP-11]]'s). The rest were all letters; 'z' indicated the revision level of that particular manual, so the first one had an 'A'.

In the second, they had the form 'ww-xxxx-yy-zzz'. 'ww' was an alphabetic code (similar to [[DEC engineering drawing numbers#Drawing codes|DECdrawing codes]]), which indicated what class of document it was. The following codes are known:

* AA - Software documentation
* AD - Addenda
* AE - [[Software Product Description]]
* AV - Reference cards
* DS - [[DEC Alpha|Alpha]] CPU/Chipset documentation
* EB - Books, including Handbooks
* EC - Alpha system component documentation
* EK - Hardware Documentation
* EY - Educational Services

The next field, 'xxxx', indicated which type of system/module the manual was for. 'yy' indicated the type of manual it was; the following typs (again, similar to drawing codes) are known:

* MM - 'Maintenance Manual'
* OP - 'Operator's Manual'
* TM - 'Technical Manual'
* UG - 'User Guide'

The 'zzz' was a number indicating the revision level of the manual at hand; it started at '001'.

==Online collections==

There are several large collections online, on/through the Internet (see links below).

Manx, in addition to indexing many online collections, once hosted copies of several collections (notably Antonio Carlini's large collection). These appear to have been removed (the reason is unknown); confusingly, Manx's database ''still contains'' links to copies of things once hosted at Manx, but the files themselves are no longer accessible. Some of the removed files are still accessible through the Internet Archive, if you have the old Manx URL. Many appear to also be available through VT100.net, but no general index to them there appears to be available; although, oddly enough, some search engines appear to know of them - perhaps because Manx itself still/now links to them!

==See also==

* [[DEC engineering drawing numbers]]
* [[:Category:DEC Documentation|DEC Documentation]]
* [[DEC Unique Product Identifier]]

==External links==

* [http://www.bitsavers.org/pdf/dec/ DEC] - the primary online collection is at [[Bitsavers]]
** [http://www.bitsavers.org/pdf/dec/catalog/MaintenancePrintPNs.txt Maintenance Print list]
* [https://manx-docs.org/ Manx] - Manx indexes many online collections of manuals
** [https://manx-docs.org/about.php About Manx]
* [https://vaxhaven.com/Documentation Documentation] - VAXHaven
* [https://wwcm.synology.me/scanned.html Main Scanned Document List] - at Wilber Williams' Computer Museum
* [https://www.mainecoon.com/classiccmp/ classiccmp] - Chris Kennedy's archive of Henk Gooijen's scans
* [https://vt100.net/ VT100.net]
* [http://chiappa.net/~jnc/tech/FMPSOnline.html 'Missing' Digital Equipment Corporation Field Maintenance Print Sets Online]

[[Category: Digital Equipment Corporation]]
[[Category: DEC Documentation]]
[[Category: DEC Naming/Numbering Schemes]]

DEC manuals

2026-10-07T06:26:54Z

Jnc: Describe issues around Manx's copies of several collections

'''DEC manuals''' were accumulated by [[Digital Equipment Corporation|DEC]] over several decades. Dating, as it did, from the early days of the industry, and originally catering primarily to engineers, who were able to repair and modify their DEC machines, it always had the habit of making available extensive documentation on its machines.

Many have now been scanned, and are available on/through the Internet; this is a huge benefit to the museums and many collectors who now keep, maintain and run collectable DEC gear.

==Identification/numbering system==

Similar to [[DEC engineering drawing numbers]], DEC manuals all had an identification 'number' (it included letters). There were two different systems: one in use up to about April, 1975; the other, thereafter.

In the first, they had the form 'DEC-ww-xxxxxx-y-z'; 'ww' was a number which indicated which [[List of Programmed Data Processors|line]] the manual was for/associated-with (e.g. "10" for the [[PDP-10]], "11" for [[PDP-11]]'s). The rest were all letters; 'z' indicated the revision level of that particular manual, so the first one had an 'A'.

In the second, they had the form 'ww-xxxx-yy-zzz'. 'ww' was an alphabetic code (similar to [[DEC engineering drawing numbers#Drawing codes|DECdrawing codes]]), which indicated what class of document it was. The following codes are known:

* AA - Software documentation
* AD - Addenda
* AE - [[Software Product Description]]
* AV - Reference cards
* DS - [[DEC Alpha|Alpha]] CPU/Chipset documentation
* EB - Books, including Handbooks
* EC - Alpha system component documentation
* EK - Hardware Documentation
* EY - Educational Services

The next field, 'xxxx', indicated which type of system/module the manual was for. 'yy' indicated the type of manual it was; the following typs (again, similar to drawing codes) are known:

* MM - 'Maintenance Manual'
* OP - 'Operator's Manual'
* TM - 'Technical Manual'
* UG - 'User Guide'

The 'zzz' was a number indicating the revision level of the manual at hand; it started at '001'.

==Online collections==

There are several large collections online, on/through the Internet (see links below).

Manx, in addition to indexing many online collections, once hosted copies of several collections (notably Antonio Carlini's large collection). These appear to have been removed (the reason is unknown); confusingly, Manx's database ''still contains'' links to copies of things once hosted at Manx, but the files themselves are no longer accessible. Some of the removed files are still accessible through the Internet Archive, if you have the old Manx URL. Many appear to also be available through VT100.net, but no general index to them there appears to be available; although, oddly enough, some search engines appear to know of them.

==See also==

* [[DEC engineering drawing numbers]]
* [[:Category:DEC Documentation|DEC Documentation]]
* [[DEC Unique Product Identifier]]

==External links==

* [http://www.bitsavers.org/pdf/dec/ DEC] - the primary online collection is at [[Bitsavers]]
** [http://www.bitsavers.org/pdf/dec/catalog/MaintenancePrintPNs.txt Maintenance Print list]
* [https://manx-docs.org/ Manx] - Manx indexes many online collections of manuals
** [https://manx-docs.org/about.php About Manx]
* [https://vaxhaven.com/Documentation Documentation] - VAXHaven
* [https://wwcm.synology.me/scanned.html Main Scanned Document List] - at Wilber Williams' Computer Museum
* [https://www.mainecoon.com/classiccmp/ classiccmp] - Chris Kennedy's archive of Henk Gooijen's scans
* [https://vt100.net/ VT100.net]
* [http://chiappa.net/~jnc/tech/FMPSOnline.html 'Missing' Digital Equipment Corporation Field Maintenance Print Sets Online]

[[Category: Digital Equipment Corporation]]
[[Category: DEC Documentation]]
[[Category: DEC Naming/Numbering Schemes]]

DEC manuals

2026-10-07T05:56:13Z

Jnc: /* External links */ +MaineCoon

DEC manuals

2026-10-07T05:31:38Z

Jnc: /* Identification/numbering system */ +EB - Books

DEC manuals

2026-10-07T05:17:43Z

Jnc: /* Identification/numbering system */ typo

Digital Equipment Corporation

2026-10-06T17:47:43Z

Jnc: /* See also */ Better location

'''Digital Equipment Corporation''', or '''DEC''', was a large computer company (at one time, the second-largest in the world after [[International Business Machines|IBM]]). They made [[minicomputer]]s, their signature product (and the one that led to their success), for a period, the most popular kind of computers in the world. Their product range eventually extended from small [[mainframe]]s to [[personal computer]]s.

It was started in 1957, in an old wool mill in Maynard, Massachusetts. The original product line was modules, [[System Module]]s. Once those were established, they started producing computers using them.

They reached the peak of their success in the 1980s, with their [[VAX]] line. However, they were unable to successfully adapt to the rise of personal computers, which turned computers into commodities, and were bought by [[Compaq]] in 1998.

{{semi-stub}}

==See also==

* [[List of Programmed Data Processors]]
* [[DEC manuals]]
* [[DEC part number]]s
* [[DEC engineering drawing numbers]]
* [[DEC acronyms]]
* [[DEC Semiconductor Chips]]
* [[DEC Packaged System Nomenclature]]
* [[Edited Option/Module List]]
* [[DEC Software-related Order Codes]]
* [[:Category:DEC Documentation Errors|DEC Documentation Errors]]
* [[:Category:DEC Hardware|DEC Hardware]]
* [[:Category:DEC Boards|DEC Boards]]
* [[:Category:DEC Architectures|DEC Architectures]]
* [[:Category:DEC Buses|DEC Buses]]
* [[:Category:DEC Systems|DEC Systems]]
* [[:Category:DEC Processors|DEC Processors]]
* [[:Category:DEC Memories|DEC Memories]]
* [[:Category:DEC Peripherals|DEC Peripherals]]
** [[:Category:DEC Storage Controllers|DEC Storage Controllers]]
** [[:Category:DEC Disk Drives|DEC Disk Drives]]
** [[:Category:DEC Tape Drives|DEC Tape Drives]]
* [[:Category:DEC Terminals|DEC Terminals]]
* [[:Category:DEC Software|DEC Software]]
** [[:Category:DEC Operating Systems|DEC Operating Systems]]
* [[DEC Modules by bus]]
* [[Digital Technical Journal]]
* [[Taxonomy of DEC consoles]]
* [[DEC indicator panel]]

==Further reading==

* Glenn Rifkin, George Harrar, ''The Ultimate Entrepreneur: The Story of Ken Olsen and Digital Equipment Corporation'', Contemporary, Chicago, 1988 - The best general history of DEC, but stops at 1987
* Edgar H. Schein, ''DEC is Dead, Long Live DEC'', Berett-Koehler, San Francisco, 2003
* Clayton M. Christensen, ''The Innovator's Dilemma: When New Technologies Cause Great Firms to Fail'', Harvard Business School, Boston, 1997 - Briefly discusses DEC's inability to adapt to the world with personal computers
* Alan R. Earls, ''Digital Equipment Corporation (Images of America)'', Arcadia, Charleston, 2004 - Mostly covers the early years

==External links==

===Books===

* [https://www.computerhistory.org/pdp-1/_media/pdf/dec.digital_1957_to_the_present_(1978).1957-1978.102630349.pdf Digital Equipment Corporation - Nineteen Fifty-Seven To the Present], 1972-78 - Thumbnail entries, but good coverage


* Jamie Parker Pearson, [http://gordonbell.azurewebsites.net/digital/digital%20at%20work%201992.pdf ''Digital at Work: Snapshots from the First Thirty-Five Years''], Digital, Burlington, 1992 - good overview with many direct quotations from DEC engineers

* C. Gordon Bell, J. Craig Mudge, John. E. McNamara, [http://gordonbell.azurewebsites.net/Computer_Engineering/contents.html Computer Engineering: A DEC View of Hardware Systems Design], Digital Press, Bedford, 1978 - a fair amount of technical detail


===Websites===

* [https://gordonbell.azurewebsites.net/Digital/DECMuseum.htm Gordon Bell's CyberMuseum for Digital Equipment Corp]
** [https://gordonbell.azurewebsites.net/Digital/timeline/dechistory.htm Digital 41 Year History CD]
** [https://gordonbell.azurewebsites.net/CGB%20Files/DEC_Is_Dead_Bell_Appendix_Schein_Book.pdf Appendix for Edgar H. Schein “DEC is Dead, Long Live DEC”] - An interesting take on where/how DEC went wrong
* [https://vt100.net/timeline/ Digital Computing Timeline (1957-1997)]
* [https://www.abortretry.fail/p/work-at-the-mill Work at the Mill] - "the Story of Digital Equipment Corporation"
* [https://web.archive.org/web/20210104122645/https://digital.com/digital-equipment-corporation/ The Tragic Tale Of DEC, The Computing Giant That Died Too Soon] (archived) 
* [http://www.decconnection.org/digitalstechnology.htm Digital's Technology Heritage]
* [https://www.ultimate.com/phil/pdp10/dec.disks DEC disk history]
* [http://www.vaxarchive.org/hardware/cables.html Cables Reference Guide]
* [http://www.avanthar.com/healyzh/decemulation/decemu.html The DEC Emulation Website]
* [https://vt100.net/dec/logo History of the Digital logo]

{{Nav DEC}}

[[Category: Manufacturers]]
[[Category: Computer Manufacturers]]
[[Category: Digital Equipment Corporation]]
[[Category: PDP-10 Users]]

Digital Equipment Corporation

2026-10-06T17:36:16Z

Jnc: /* See also */ +DEC manuals

'''Digital Equipment Corporation''', or '''DEC''', was a large computer company (at one time, the second-largest in the world after [[International Business Machines|IBM]]). They made [[minicomputer]]s, their signature product (and the one that led to their success), for a period, the most popular kind of computers in the world. Their product range eventually extended from small [[mainframe]]s to [[personal computer]]s.

It was started in 1957, in an old wool mill in Maynard, Massachusetts. The original product line was modules, [[System Module]]s. Once those were established, they started producing computers using them.

They reached the peak of their success in the 1980s, with their [[VAX]] line. However, they were unable to successfully adapt to the rise of personal computers, which turned computers into commodities, and were bought by [[Compaq]] in 1998.

{{semi-stub}}

==See also==

* [[List of Programmed Data Processors]]
* [[DEC manuals]]
* [[DEC part number]]s
* [[DEC engineering drawing numbers]]
* [[DEC acronyms]]
* [[DEC Semiconductor Chips]]
* [[DEC Packaged System Nomenclature]]
* [[Edited Option/Module List]]
* [[DEC Software-related Order Codes]]
* [[Taxonomy of DEC consoles]]
* [[:Category:DEC Documentation Errors|DEC Documentation Errors]]
* [[:Category:DEC Hardware|DEC Hardware]]
* [[:Category:DEC Boards|DEC Boards]]
* [[:Category:DEC Architectures|DEC Architectures]]
* [[:Category:DEC Buses|DEC Buses]]
* [[:Category:DEC Systems|DEC Systems]]
* [[:Category:DEC Processors|DEC Processors]]
* [[:Category:DEC Memories|DEC Memories]]
* [[:Category:DEC Peripherals|DEC Peripherals]]
** [[:Category:DEC Storage Controllers|DEC Storage Controllers]]
** [[:Category:DEC Disk Drives|DEC Disk Drives]]
** [[:Category:DEC Tape Drives|DEC Tape Drives]]
* [[:Category:DEC Terminals|DEC Terminals]]
* [[:Category:DEC Software|DEC Software]]
** [[:Category:DEC Operating Systems|DEC Operating Systems]]
* [[DEC Modules by bus]]
* [[Digital Technical Journal]]
* [[DEC indicator panel]]

==Further reading==

* Glenn Rifkin, George Harrar, ''The Ultimate Entrepreneur: The Story of Ken Olsen and Digital Equipment Corporation'', Contemporary, Chicago, 1988 - The best general history of DEC, but stops at 1987
* Edgar H. Schein, ''DEC is Dead, Long Live DEC'', Berett-Koehler, San Francisco, 2003
* Clayton M. Christensen, ''The Innovator's Dilemma: When New Technologies Cause Great Firms to Fail'', Harvard Business School, Boston, 1997 - Briefly discusses DEC's inability to adapt to the world with personal computers
* Alan R. Earls, ''Digital Equipment Corporation (Images of America)'', Arcadia, Charleston, 2004 - Mostly covers the early years

==External links==

===Books===

* [https://www.computerhistory.org/pdp-1/_media/pdf/dec.digital_1957_to_the_present_(1978).1957-1978.102630349.pdf Digital Equipment Corporation - Nineteen Fifty-Seven To the Present], 1972-78 - Thumbnail entries, but good coverage


* Jamie Parker Pearson, [http://gordonbell.azurewebsites.net/digital/digital%20at%20work%201992.pdf ''Digital at Work: Snapshots from the First Thirty-Five Years''], Digital, Burlington, 1992 - good overview with many direct quotations from DEC engineers

* C. Gordon Bell, J. Craig Mudge, John. E. McNamara, [http://gordonbell.azurewebsites.net/Computer_Engineering/contents.html Computer Engineering: A DEC View of Hardware Systems Design], Digital Press, Bedford, 1978 - a fair amount of technical detail


===Websites===

* [https://gordonbell.azurewebsites.net/Digital/DECMuseum.htm Gordon Bell's CyberMuseum for Digital Equipment Corp]
** [https://gordonbell.azurewebsites.net/Digital/timeline/dechistory.htm Digital 41 Year History CD]
** [https://gordonbell.azurewebsites.net/CGB%20Files/DEC_Is_Dead_Bell_Appendix_Schein_Book.pdf Appendix for Edgar H. Schein “DEC is Dead, Long Live DEC”] - An interesting take on where/how DEC went wrong
* [https://vt100.net/timeline/ Digital Computing Timeline (1957-1997)]
* [https://www.abortretry.fail/p/work-at-the-mill Work at the Mill] - "the Story of Digital Equipment Corporation"
* [https://web.archive.org/web/20210104122645/https://digital.com/digital-equipment-corporation/ The Tragic Tale Of DEC, The Computing Giant That Died Too Soon] (archived) 
* [http://www.decconnection.org/digitalstechnology.htm Digital's Technology Heritage]
* [https://www.ultimate.com/phil/pdp10/dec.disks DEC disk history]
* [http://www.vaxarchive.org/hardware/cables.html Cables Reference Guide]
* [http://www.avanthar.com/healyzh/decemulation/decemu.html The DEC Emulation Website]
* [https://vt100.net/dec/logo History of the Digital logo]

{{Nav DEC}}

[[Category: Manufacturers]]
[[Category: Computer Manufacturers]]
[[Category: Digital Equipment Corporation]]
[[Category: PDP-10 Users]]

DEC documentation

2026-10-06T17:29:35Z

Jnc: Redir - alt term

#Redirect [[DEC manuals]]

DEC manuals

2026-10-06T17:27:14Z

Jnc: Another place to accumulate useful URL's

DEC part number

2026-10-06T13:20:22Z

Jnc: /* External links */ ManX has ditched Antonio's collection

'''DEC part numbers''' are generally of the form 'ww-xxxxx-yy zzzz' (sometimes the first hyphen is omitted). [[Digital Equipment Corporation|DEC]] had a system for their part numbers, such that looking at a part number will generally tell you (based on the leading two-digit field, the 'class code') what ''kind'' of part it is: [[integrated circuit|chip]], cable, etc. The next field is a 'basic identifier', then comes a 'variation identifier'; the final, optional, field is the 'revision identifier'.

It should be noted that DEC had several other [[namespace]]s for things produced by the company (such as [[DEC engineering drawing numbers]]; and the identification numbers of [[FLIP CHIP]]s and later component [[printed circuit board|PCBs]], of the form 'Xyyyy', where 'X' is a capital letter, and 'yyyy' are digits), but these numbers are ''not'' 'DEC part numbers', as defined by the applicable DEC specifications (below).

This table lists the major class codes:

{| class="wikitable"
! Class !! Type
|-
| 10 || [[Capacitor]]s
|-
| 11 || [[Diode]]s
|-
| 12 || Mechanical and electro-mechanical items ([[connector]]s, [[connector|pins]], bearings, belts, fans, etc)
|-
| 13 || [[Resistor]]s
|-
| 15 || [[Transistor]]s
|-
| 16 || [[Transformer]]s and [[inductor]]s
|-
| 17 || Wire and [[fiber optic]] cables
|-
| 18 || [[Crystal]]s and other oscillators
|-
| 19 || [[Bipolar]] [[integrated circuit]]s
|-
| 21 || [[Metal Oxide Semiconductor|MOS]] chips ([[Central Processing Unit|CPUs]], etc)
|-
| 23 || Fixed memory chips ([[Read-only memory|ROMs]], etc)
|-
| 24 || Fiber-optic components
|-
| 30 || [[Core memory]] stacks, major components
|-
| 36 || [[Paper tape]], [[punched card]]s, labels
|-
| 50 || [[Printed circuit board]]s
|-
| 52 || Pulse transformers
|-
| 54 || Assemblies (circuit cards, [[DEC indicator panel|display panels]], etc)
|-
| 70 || Cables/[[harness]]es/[[backplane]]s
|-
| 74 || 'Manufactured non-electrical parts' (includes decals, etc)
|-
| 90 || Fastener hardware (nuts, bolts, screws, washers, ties etc)
|-
| 91 || Hook up wire and tubing
|}


==External links==

* [https://web.archive.org/web/20240505223523/https://manx-docs.org/collections/antonio/dec/standards/el-00012-00-0000.pdf DEC STD 012-0 Part Identification Standard]
* [https://web.archive.org/web/20240505223523/https://manx-docs.org/collections/antonio/dec/standards/el-00012-02-0000.pdf DEC STD 012-2 Unified Numbering Code for Part Identiﬁer Class Codes]
* [https://how-to.fandom.com/wiki/How_to_identify_computer_chips_or_integrated_circuits_on_circuit_boards How to identify computer chips or integrated circuits on circuit boards]

[[Category: Digital Equipment Corporation]]
[[Category: DEC Naming/Numbering Schemes]]

Digital Equipment Corporation

2026-10-06T12:15:04Z

Jnc: /* Websites */ Add a few

'''Digital Equipment Corporation''', or '''DEC''', was a large computer company (at one time, the second-largest in the world after [[International Business Machines|IBM]]). They made [[minicomputer]]s, their signature product (and the one that led to their success), for a period, the most popular kind of computers in the world. Their product range eventually extended from small [[mainframe]]s to [[personal computer]]s.

It was started in 1957, in an old wool mill in Maynard, Massachusetts. The original product line was modules, [[System Module]]s. Once those were established, they started producing computers using them.

They reached the peak of their success in the 1980s, with their [[VAX]] line. However, they were unable to successfully adapt to the rise of personal computers, which turned computers into commodities, and were bought by [[Compaq]] in 1998.

{{semi-stub}}

==See also==

* [[List of Programmed Data Processors]]
* [[Taxonomy of DEC consoles]]
* [[DEC indicator panel]]
* [[DEC Semiconductor Chips]]
* [[DEC part number]]s
* [[DEC engineering drawing numbers]]
* [[DEC acronyms]]
* [[DEC Software-related Order Codes]]
* [[DEC Packaged System Nomenclature]]
* [[Edited Option/Module List]]
* [[:Category:DEC Documentation Errors|DEC Documentation Errors]]
* [[:Category:DEC Hardware|DEC Hardware]]
* [[:Category:DEC Boards|DEC Boards]]
* [[:Category:DEC Architectures|DEC Architectures]]
* [[:Category:DEC Buses|DEC Buses]]
* [[:Category:DEC Systems|DEC Systems]]
* [[:Category:DEC Processors|DEC Processors]]
* [[:Category:DEC Memories|DEC Memories]]
* [[:Category:DEC Peripherals|DEC Peripherals]]
** [[:Category:DEC Storage Controllers|DEC Storage Controllers]]
** [[:Category:DEC Disk Drives|DEC Disk Drives]]
** [[:Category:DEC Tape Drives|DEC Tape Drives]]
* [[:Category:DEC Terminals|DEC Terminals]]
* [[:Category:DEC Software|DEC Software]]
** [[:Category:DEC Operating Systems|DEC Operating Systems]]
* [[DEC Modules by bus]]
* [[Digital Technical Journal]]

==Further reading==

* Glenn Rifkin, George Harrar, ''The Ultimate Entrepreneur: The Story of Ken Olsen and Digital Equipment Corporation'', Contemporary, Chicago, 1988 - The best general history of DEC, but stops at 1987
* Edgar H. Schein, ''DEC is Dead, Long Live DEC'', Berett-Koehler, San Francisco, 2003
* Clayton M. Christensen, ''The Innovator's Dilemma: When New Technologies Cause Great Firms to Fail'', Harvard Business School, Boston, 1997 - Briefly discusses DEC's inability to adapt to the world with personal computers
* Alan R. Earls, ''Digital Equipment Corporation (Images of America)'', Arcadia, Charleston, 2004 - Mostly covers the early years

==External links==

===Books===

* [https://www.computerhistory.org/pdp-1/_media/pdf/dec.digital_1957_to_the_present_(1978).1957-1978.102630349.pdf Digital Equipment Corporation - Nineteen Fifty-Seven To the Present], 1972-78 - Thumbnail entries, but good coverage


* Jamie Parker Pearson, [http://gordonbell.azurewebsites.net/digital/digital%20at%20work%201992.pdf ''Digital at Work: Snapshots from the First Thirty-Five Years''], Digital, Burlington, 1992 - good overview with many direct quotations from DEC engineers

* C. Gordon Bell, J. Craig Mudge, John. E. McNamara, [http://gordonbell.azurewebsites.net/Computer_Engineering/contents.html Computer Engineering: A DEC View of Hardware Systems Design], Digital Press, Bedford, 1978 - a fair amount of technical detail


===Websites===

* [https://gordonbell.azurewebsites.net/Digital/DECMuseum.htm Gordon Bell's CyberMuseum for Digital Equipment Corp]
** [https://gordonbell.azurewebsites.net/Digital/timeline/dechistory.htm Digital 41 Year History CD]
** [https://gordonbell.azurewebsites.net/CGB%20Files/DEC_Is_Dead_Bell_Appendix_Schein_Book.pdf Appendix for Edgar H. Schein “DEC is Dead, Long Live DEC”] - An interesting take on where/how DEC went wrong
* [https://vt100.net/timeline/ Digital Computing Timeline (1957-1997)]
* [https://www.abortretry.fail/p/work-at-the-mill Work at the Mill] - "the Story of Digital Equipment Corporation"
* [https://web.archive.org/web/20210104122645/https://digital.com/digital-equipment-corporation/ The Tragic Tale Of DEC, The Computing Giant That Died Too Soon] (archived) 
* [http://www.decconnection.org/digitalstechnology.htm Digital's Technology Heritage]
* [https://wwcm.synology.me/scanned.html Main Scanned Document List] - at Wilber Williams' Computer Museum
* [https://www.ultimate.com/phil/pdp10/dec.disks DEC disk history]
* [http://www.vaxarchive.org/hardware/cables.html Cables Reference Guide]
* [http://www.avanthar.com/healyzh/decemulation/decemu.html The DEC Emulation Website]
* [https://vt100.net/dec/logo History of the Digital logo]

{{Nav DEC}}

[[Category: Manufacturers]]
[[Category: Computer Manufacturers]]
[[Category: Digital Equipment Corporation]]
[[Category: PDP-10 Users]]

UNIBUS Initialization

2026-10-06T12:02:47Z

Jnc: /* External links */ Bitsavers has reorganized a bit

The is an exact transcription of the "Initialization Section" section (pp. 52-56) of the "pdp11 bus handbook" ([[Digital Equipment Corporation|DEC]], 1979).

=Initialization Section=

The Initialization section of the UNIBUS controls initializing or resetting, and the power-up and power-down sequences of all bus devices. Three UNIBUS signals are used: INIT, AC LO, and DC LO.

==Initialization (INIT)==

INIT is caused by some console operations, the RESET instruction, and DC LO. Only a processor, or the arbitrator, may assert INIT.

===Processor Requirements===

A processor must become bus master, then wait for 5 μseconds before it may assert INIT. No bus cycles may be executed during these 5 μseconds. This delay ensures that all memory cycles in progress are complete before asserting INIT.

However, if a processor tries to assert INIT but cannot obtain the use of the data section of the bus after 100 μseconds, it may then assert INIT without becoming bus master.

A processor, as bus master through a grant sequence, may not negate SACK until after it asserts INIT. This ensures that the arbitrator receives the assertion of INIT before the negation of SACK. This prevents the arbitrator from starting arbitration until it receives the negation of INIT.

Any processor, after negating INIT, must wait 75 nseconds before asserting any signal, except AC LO, DC LO, or INIT. This ensures that the negation of INIT reaches all bus devices before the processor asserts any signal on the data section of the bus.

===Arbitrator Response===

Upon receipt of the assertion of INIT, the arbitrator negates all grants and may not issue any for events that occurred before INIT. No grant may be issued while INIT is asserted.

===Master/Slave Device Response===

When a master/slave device receives the assertion of INIT, it responds as follows.

# It completes any bus cycle in process. If the device is bus master, then it negates BBSY. If the bus cycle in progress is a DATIP, the master completes the DATO/B. The memory must be capable of completing the DATO/B, or it must restore itself and treat any following DATO/B as a new transaction.
# It negates any of the following signals that it may be asserting: SACK, NPR, BR4, BR5, BR6, BR7; and it passes all grants.
# It clears the Interrupt Enable bit. It may assert AC LO, DC LO, and any signal required by step 1 above. It may not assert NPR, BR, SACK, or BBSY.

After receipt of the negation of INIT, a device must be reset for normal programming. If the device is not ready, it may set a busy bit until its internal initialization sequence is finished. The device may have an error condition set. Some of the device registers may contain new or old values. The contents of these registers after receipt of the negation of INIT should be defined in the device specification. Devices should retain as much status information as possible in order to make error analysis easier.

A device is not required to buffer commands received during its internal initialization sequence, provided it sets a bit indicating that it is not ready to accept commands (busy bit).

==Power-up and Power-down Sequences==

The purpose of the power-up and power-down sequences is to guarantee time to store (on power-down) and retrieve (on power-up) the program parameters required for continued operation.

A DC power failure, as used here, means that DC power has dropped below its minimum operating level.


# When power is off in any UNIBUS device, AC LO and DC LO are asserted and all other UNIBUS signals are undefined.
# When the DC voltage to the processor rises to a level at which the logic elements operate, DC LO initializes the processor with BBSY and INIT asserted.
# (''Power-up'') DC Lo is negated by the power supply 5 μseconds after DC power is within specifications.
# INIT remains asserted for a minimum of 10 mseconds after receipt of the negation of DC LO. This provides time for initialization of most bus devices.
# The processor waits a minimum of 70 mseconds after the negation of DC LO to allow all bus devices to complete their internal initialization operations.
# Before or at the end of this 70 msecond delay, INIT is negated. The processor then tests AC LO. When it senses the negation AC LO, the processor starts its power-up sequenc; and the arbitrator is enabled. AC LO must not be negated by the power supply for less than 1 μsecond.
NOTE: While AC LO is negated, DC power is guaranteed to be within specifications for a minimum of 5 mseconds + 5 μseconds.
<ol start="7">
<li>The processor waits a minimum of 2 mseconds before testing AC LO again. These 2 mseconds are used by the processor for its power-up sequence.</li>
<li>Having completed its power-up sequence, the processor continuously monitors AC LO.</li>
<li>(''Power-down'') Upon receipt of the assertion of AC LO, a processor starts it power-down routine. (AC LO must not be asserted by the power supply for less than 1 μsecond.) The processor does not test AC LO again until its next power-up sequence.</li>
<li>For a minimum of 2 mseconds, and a maximum of 3 mseconds, the processor asserts BBSY and does not use the data section of the bus. It stops execution of programs.</li>
<li>A minimum of 5 μseconds later, the processor asserts DC LO for at least 1 μsecond. This, in turn, asserts INIT for same time period.</li>
<li>The subsequent negation of DC LO by the processor is the beginning of a power-up sequence, as in step 3 above. DC LO may be held asserted by a power-supply or by another bus device.</li>
<li>DC LO must not be asserted by the power supply for a minimum of 5 mseconds after it asserts AC LO. The ensures enough time is available for a complete power-up and power-down cycle.</li>
<li>DC power must be within specification for a minimum of 5 μseconds after the assertion of DC LO by the power supply.</li>
</ol>
NOTE: The power-up sequence starts at the negation of AC LO 70 mseconds after negation of DC LO. AC LO is not tested during the 2 mseconds allotted to the power-up sequence. It follows that if AC LO is re-asserted before the end of the power-up sequence (2 mseconds), the power-down sequence (2-3 mseconds) must be performed immediately following the power-up sequence. This requires a 5 msecond minimum of guaranteed DC power at the negation of AC LO. This also implies that 5 mseconds of guaranteed DC power is available at any time while AC LO is negated.

A ''brown-out'' occurs when AC LO is asserted, but DC power is within specifications. (DC LO is negated). In this case, the processor waits for the negation of AC LO as in step 6 above.

==External links==

* [http://www.bitsavers.org/pdf/dec/pdp11/handbooks/PDP-11_Bus_Handbook_1979.pdf pdp11 bus handbook] - at [[Bitsavers]]

[[Category: UNIBUS]]
[[Category: DEC Documentation]]

DLV11-F asynchronous serial line interface

2026-10-06T09:41:38Z

Jnc: /* External links */ Bitsavers has reorganized a bit; fix Manx lossage

[[Image:DLV11-F RevD.jpg|thumb|right|300px|DLV11-F M8028 board etch revision D]]

The '''DLV11-F asynchronous serial line interface''' card (M8028) was a [[QBUS]] [[peripheral]] for the [[PDP-11]] series of computers which provided an [[asynchronous serial line]] on a single [[DEC card form factor|dual-width]] card.

It provided both [[EIA RS-232 serial line interface|EIA RS-232]] (with vestigial [[modem]] control), and [[20mA current loop serial line interface#'Active' and 'passive' modes|active or passive]] [[20mA current loop serial line interface|20 mA]] connectivity. [[Baud rate]]s from 50 to 19,200 were available; receive and transmit can be set independently via configuration [[jumper]]s, or can be set via the [[register]]s, if desired (although not input and output independently; either transmit only, or both).

Line connection was via 40-pin [[Berg connector]] headers on the top edge of the card, using the standard [[DEC asynchronous serial line pinout]].

Configuration was via [[wire-wrap]] [[jumper]]s.

==Programing interface==

Like the ancestral [[KL11 asynchronous serial line interface|KL11]], the DLV11 has 2 device registers for the receive side (one Control and Status Register - CSR - and one data [[buffer]] register), and similarly, two for the transmit side. Each line has two [[interrupt vector]]s - again, one receive, and one transmit.

For the PDP-11 main console (which is always a KL11/DL11 compatible device), the standard is that 0777560 is the base address (so the receiver registers are 0777560-2, and the transmitter are 0777564-6), and 060 is the base vector. It can be set to [[halt]] the [[Central Processing Unit|CPU]] when a '[[asynchronous serial line|break]]' is seen; it can also send a 'break'.

The first line after the console is always assigned the address 0776500, and vector 0300. Additional lines are assigned addresses and vectors immediately following, for DL11's #1-#16 (i.e. 0776500-676 and 0300-0476).

==Layout==

The 'Revison C' and later [[printed circuit board|PCB]] layouts are significantly different from the earlier ones; it is easy to recognize these versions visually, as the large [[asynchronous serial line#UART|UART]] chip is parallel to the long axis of the card. These versions are not covered in most DLV11-F documentation; they can be found in the ''"Microcomputer Interfaces Handbook"'' (1980), on pg. 207.

==See also==

* [[DLV11 asynchronous serial line interface]]
* [[DLV11-E asynchronous serial line interface]]
* [[DLV11-J asynchronous serial line interface]]

==Further reading==

* ''DLV11-F Replacement for the DLV11'', [[MicroNote]] #046A

==External links==

* [http://www.bitsavers.org/pdf/dec/qbus/DLV11/EK-DLV11-OP-001_DLV11-E_and_DLV11-F_Asynchronous_Line_Interface_Users_Manual_Jun77.pdf DLV11-E and DLV11-F asynchronous line interface user's manual] (EK-DLV11-OP-001)
* [http://www.bitsavers.org/pdf/dec/qbus/EB-20175-20_Digital_Microcomputer_Interfaces_Handbook_1980.pdf Microcomputer Interfaces Handbook] - the DLV11-F, Revisions C and up, is covered on pp. 207
* [https://vt100.net/mirror/hcps/DLV11.pdf DLV11-F Field Maintenance Print Set] (MP00461)

[[Category: QBUS Asynchronous Serial Interfaces]]

DLV11-E asynchronous serial line interface

2026-10-06T09:09:56Z

Jnc: /* External links */ Bitsavers has reorganized a bit

[[Image:DLV11-E RevC.jpg|thumb|right|300px|DLV11-E M8017 board etch revision C]]

The '''DLV11-E asynchronous serial line interface''' card was a [[QBUS]] [[peripheral]] for the [[PDP-11]] series of computers which provided an [[asynchronous serial line]] on a single [[DEC card form factor|dual-width]] card ('''M8017''') .

It provided [[EIA RS-232 serial line interface|EIA RS-232]] connectivity; it also had full [[modem]] control. [[Baud rate]]s from 50 to 19,200 were available; receive and transmit can be set independently via configuration [[jumper]]s, or can be set via the [[register]]s, if desired (although not input and output independently; either transmit only, or both).

Line connection was via 40-pin [[Berg connector]] headers on the top edge of the card, using the standard [[DEC asynchronous serial line pinout]].

Configuration was via [[wire-wrap]] [[jumper]]s.

==Programing interface==

Like the ancestral [[KL11 asynchronous serial line interface|KL11]], the DLV11 has 2 device registers for the receive side (one Control and Status Register - CSR - and one data [[buffer]] register), and similarly, two for the transmit side. Each line has two [[interrupt vector]]s - again, one receive, and one transmit.

For the PDP-11 main console (which is always a KL11/DL11 compatible device), the standard is that 0777560 is the base address (so the receiver registers are 0777560-2, and the transmitter are 0777564-6), and 060 is the base vector. It can be set to [[halt]] the [[Central Processing Unit|CPU]], or [[bootstrap|re-boot]] the system, when a '[[asynchronous serial line|break]]' is seen; it can also send a 'break'.

The first line after the console is always assigned the address 0776500, and vector 0300. Additional lines are assigned addresses and vectors immediately following, for DL11's #1-#16 (i.e. 0776500-676 and 0300-0476).

[[Image:DLV11-E RevD.jpg|thumb|left|300px|DLV11-E M8017 board etch revision D]]

==Layout==

The 'Revison D' [[printed circuit board|PCB]] layout is significantly different from the earlier ones; it is easy to recognize this version visually, as the large [[asynchronous serial line#UART|UART]] chip is parallel to the long axis of the card. This version is not covered in most DLV11-E documentation; it can be found in the ''"Microcomputer Products Handbook"'' (1985), on pg. 22-3.

==See also==

* [[DLV11 asynchronous serial line interface]]
* [[DLV11-F asynchronous serial line interface]]
* [[DLV11-J asynchronous serial line interface]]

==External links==

* [http://www.bitsavers.org/pdf/dec/qbus/DLV11/EK-DLV11-OP-001_DLV11-E_and_DLV11-F_Asynchronous_Line_Interface_Users_Manual_Jun77.pdf DLV11-E and DLV11-F asynchronous line interface user's manual] (EK-DLV11-OP-001)
* [http://www.bitsavers.org/pdf/dec/qbus/EB-26078-41_Digital_Microcomputer_Products_Handbook_1985.pdf Microcomputer Products Handbook] - the DLV11-E, Revision D is covered on pp. 22–3-5 (pp. 295-297 of the PDF)
* [http://www.bitsavers.org/pdf/dec/qbus/MP00706-ET-LSI-11_Dec81.pdf ET-LSI11 Field Maintenance Print Set] - the ''DLV11-E Field Maintenance Print Set'' (MP00460) is on pp. 32-37

[[Category: QBUS Asynchronous Serial Interfaces]]

DLV11 asynchronous serial line interface

2026-10-06T09:05:43Z

Jnc: /* External links */ Bitsavers has reorganized a bit

[[Image:DLV11_M7940.jpg|thumb|right|300px|DLV11 M7940 board]]

The '''DLV11 asynchronous serial line interface''' card (M7940) was a [[QBUS]] [[peripheral]] for the [[PDP-11]] series of computers which provided an [[asynchronous serial line]] on a single [[DEC card form factor|dual-width]] card.

It provided both [[EIA RS-232 serial line interface|EIA RS-232]], and active or passive [[20mA current loop serial line interface|20 mA]] connectivity, at speeds of 110 to 9600 [[baud rate|baud]]; it had vestigial [[modem]] control. Line connection was via 40-pin [[Berg connector]] headers on the top edge of the card, using the standard [[DEC asynchronous serial line pinout]].

Configuration was via [[wire-wrap]] [[jumper]]s.

==Programing interface==

Like the ancestral [[KL11 asynchronous serial line interface|KL11]], the DLV11 has 2 device [[register]]s for the receive side (one Control and Status Register - CSR - and one data [[buffer]] register), and similarly, two for the transmit side. Each line has two [[interrupt vector]]s - again, one receive, and one transmit.

For the PDP-11 main console (which is always a KL11/DL11 compatible device), the standard is that 0777560 is the base address (so the receiver registers are 0777560-2, and the transmitter are 0777564-6), and 060 is the base vector. It can be set to [[halt]] the [[Central Processing Unit|CPU]] when a '[[asynchronous serial line|break]]' is seen.

The first line after the console is always assigned the address 0776500, and vector 0300. Additional lines are assigned addresses and vectors immediately following, for DL11's #1-#16 (i.e. 0776500-676 and 0300-0476).

==See also==

* [[DLV11-E asynchronous serial line interface]]
* [[DLV11-F asynchronous serial line interface]]
* [[DLV11-J asynchronous serial line interface]]

==External links==

* [http://www.bitsavers.org/pdf/dec/pdp11/1103/EK-LSI11-TM-002.pdf LSI-11, PDP-11/03 user's manual] (EK-LSI11-TM-002) - the DLV11 is covered in Sections 4.7 (pp. 68-73 of the PDF) and 6.2 (pp. 91-95)
* [http://www.bitsavers.org/pdf/dec/qbus/EB-20175-20_Digital_Microcomputer_Interfaces_Handbook_1980.pdf microcomputer interfaces handbook] - the DLV11 is covered on pp. 173-187 of the PDF
* [http://www.bitsavers.org/pdf/dec/qbus/EB-26078-41_Digital_Microcomputer_Products_Handbook_1985.pdf Microcomputer Products Handbook] - the DLV11 is covered in Chapter 21 (pp. 285-291 of the PDF)
* [http://www.bitsavers.org/pdf/dec/qbus/DLV11/MP00055_DLV11_Jun76.pdf DLV11 Field Maintenance Print Set] (MP00055)

[[Category: QBUS Asynchronous Serial Interfaces]]

DLV11-J asynchronous serial line interface

2026-10-06T08:58:18Z

Jnc: /* External links */ Bitsavers has reorganized a bit

[[Image:DLV11-J.jpg|thumb|right|300px|DLV11-J M8043 board]]

The '''DLV11-J asynchronous serial line interface''' card was a [[QBUS]] [[peripheral]] for the [[PDP-11]] series of computers which provided four [[asynchronous serial line]]s on a single [[DEC card form factor|dual-width]] card, the M8043.

It provided both [[EIA RS-232 serial line interface|EIA RS-232]] or [[EIA RS-422 serial line interface|RS-422]] connectivity at speeds of 150 to 38.4K [[baud rate|baud]]; receive and transmit speeds are the same on each line, but each line could be set independently. It did not have any [[modem]] control. [[20mA current loop serial line interface|20mA]] operation was possible with the [[DLV11-KA 20mA Current Loop Option]].

Line connection was via four separate 10-pin [[Berg connector]] headers on the top edge of the card, using the standard [[DEC asynchronous serial line pinout]].

Configuration was via [[wire-wrap]] [[jumper]]s.

==Programing interface==

Like the ancestral [[KL11 asynchronous serial line interface|KL11]], for each line the DL11-J has 2 device [[register]]s for the receive side (one Control and Status Register - CSR - and one data [[buffer]] register), and similarly, two for the transmit side. Each line has two [[interrupt vector]]s - again, one receive, and one transmit. The DLV11-J is [[program compatible]] with other KL11-type interfaces.

Normally both the registers and interrupt vectors are in contiguous blocks for the 4 lines, but there are special provisions for one line to be configured as the PDP-11 main console (which is always a KL11/DL11 compatible device). The standard there is that 0777560 is the base address (so the receiver registers are 0777560-2, and the transmitter are 0777564-6), and 060 is the base vector.

That line can be set to [[halt]] the [[Central Processing Unit|CPU]], or [[bootstrap|re-boot]] the system, when a '[[asynchronous serial line|break]]' is seen. All lines can send a 'break'.

The first line after the console is always assigned the address 0776500, and vector 0300. Additional lines are assigned addresses and vectors immediately following, for DL11's #1-#16 (i.e. 0776500-676 and 0300-0476).

==Cabling==

There are several options for cabling to the DLV11-J. One is to run individual cables, such as the BC20N-xx (Berg 10-pin connector, to [[EIA RS-232 serial line interface#Connectors|female DB-25S wired as a DCE]] - i.e. including a [[EIA RS-232 serial line interface|null modem]]) to each line's Berg connector. The alternative approach is that DEC produced a number of [[distribution panel]]s which can be used with the DLV11-J; all have a [[flat cable]] which splits into four sub-cables, each with a Berg 10-pin connector which plugs into one of the Berg headers on the DLV11-J.

One is the D315; it has four male DB-25P connectors, i.e. wired as a DTE. It comes in two variants: in both, the flat cable is soldered directly to a [[printed circuit board|PCB]]: in one, that contains the final DB-25P connectors; in the other, they are mounted in a subsidiary plate, and each one has a built-in [[static filter]].

Another 4-port distribution panel has a Berg 40-pin header; a flat cable with 4 Berg 10-pin connectors plugs into that. It can be identified by the [[DEC part numbers|DEC part number]] on the PCB it uses; 50-15220-01 (the part number for the complete assembly is 54-15221). It is possible that the similar 70-19964-01 (used with the [[DZV11 asynchronous serial line interface|DZV11]]), would also work (its PCB part number is 50-15419; the part number for the complete assembly is 54-15420).

==See also==

* [[DLV11 asynchronous serial line interface]]
* [[DLV11-E asynchronous serial line interface]]
* [[DLV11-F asynchronous serial line interface]]

==Further reading==

* ''DLV11-J Cabling'', [[MicroNote]] #056
* ''Maximum Configuration of DLV11-J Modules'', MicroNote #060
* ''DLV11-J Receiver Chip Problem'', MicroNote #067A

==External links==

* [http://www.bitsavers.org/pdf/dec/qbus/DLV11-J/EK-DLV1J-UG-001_DLV11-J_Users_Guide_Oct78.pdf DLV11-J user's manual] (EK-DLV1J-UG-001)
* [http://www.bitsavers.org/pdf/dec/qbus/DLV11-J/MP00586_DLV11-J_Feb78.pdf DLV11-J Field Maintenance Print Set] (MP00586)
* [http://www.bitsavers.org/pdf/dec/qbus/DLV11-J/MP00990_CKDLVJ1_Engineering_Drawings_Aug85.pdf CKDLVJ1 Field Maintenance Print Set] (MP00990-01) - distribution panel cabinet kit

[[Category: QBUS Asynchronous Serial Interfaces]]

MS11-P MOS memory

2026-10-06T08:54:20Z

Jnc: /* External links */ Bitsavers has reorganized a bit

[[Image:MS11-P.jpg|300px|thumb|right|MS11-P board]]

The '''MS11-P''' (formally, the '''MS11-PB'''; if there was an MS11-PA, nothing is now known of it) is a [[Extended UNIBUS]] [[Metal Oxide Semiconductor|MOS]] [[Dynamic RAM|DRAM]] [[main memory]] card. As an EUB card, it can therefore ''only'' be plugged into the EUB slots on the [[PDP-11/24]] or [[PDP-11/44]] [[backplane]].

It has [[Error-correcting code|ECC]] which automagically corrects single-[[bit]] errors,  and detects double-bit errors. On power-on, the system is frozen (via negation of the ACLO UNIBUS signal) while the entire memory is cleared, to prevent spurious ECC errors. For [[diagnostic]] purposes, the ECC can be disabled, and there are also means for the CPU to read/write the ECC bits directly.

The [[access time]] is 490-535 nsec (read, typical/max; 215-230 nsec extra on error), 100-125 nsec (write); the [[cycle time]] is 680-750 nsec (read cycle) or 580-620 (write cycle). [[Memory refresh]] time is 675 nsec (typical; 725 nsec maximum), every 11.25-13.75 μsec. 

It is a [[DEC card form factor|hex-height]] card, the '''M8743''', and holds 1 Mbyte when fully populated with 64Kx1 DRAM [[integrated circuit|chips]]. The memory is arranged as 8 banks, each 16 data bits wide, with 6 additional bits for the ECC.

It uses +5V only, unlike the earlier [[MS11-L MOS memory|MS11-L]] and [[MS11-M MOS memory|MS11-M]] MOS memories. The board has provision to use battery backup power to retain data during a power outage. Power requirements are 3.4-4.8A of +5V, and 2.0-2.8A of +5VBB.

==External links==

* [http://bitsavers.org/pdf/dec/brochures/DEC-MS11-PB-UNIBUS-Memory.pdf MS11-PB UNIBUS Memory] - brochure
* [http://bitsavers.org/pdf/dec/pdp11/memory/MS11-P/EK-MS11P-TM-001_Tech_Oct82.pdf MS11-P MOS Memory Technical Manual] (EK-MS11P-TM-001)
* [http://bitsavers.org/pdf/dec/pdp11/memory/MS11-P/MP01477_MS11P_Sep82.pdf MS11-P Field Maintenance Print Set] (MP01477)

[[Category: EUB Memories]]

H777 Power Supply

2026-10-06T08:50:12Z

Jnc: /* External links */ Bitsavers has reorganized a bit

The '''H777 Power Supply''' is the [[power supply]] unit for the [[BA11-L mounting box]] from [[Digital Equipment Corporation|DEC]]. It provided [[direct current|DC]] [[current]] at [[voltage]]s of +5V, +15V and -15V, with optional +20V/-5V for use with [[core memory]]. A later variant (used for the [[PDP-11/24]] in the BA11-L box) also provided +15V/-15V for use by its [[EIA RS-232 serial line interface|RS232]] [[asynchronous serial line]]s.

An optional '''H775A Battery Backup Unit''' allowed provision of power to [[Metal Oxide Semiconductor|MOS]] [[main memory]] units mounted in the BA11-L, allowing their contents to be retained during brief power outages.

A combination of up to 3 modules, composed of [[printed circuit board|boards]] with integral [[heat sink]]s, provided different combinations of output voltages:

* +5V Regulator - [[DEC part number]] 70-11073 or 70-12909 (all configurations had to include one of these)
* MOS Regulator, +/- 15V, +5VB - 54-11601
* Core Regulator, +20V, -5V - 54-11599

There are a large number of different models of the H777, but they boil down to a combination of three (later four) options:

* 110V or 220V [[alternating current|AC]] input
* The optional +20V/-5V core supply
* An upgraded +5V power supply (70-12909) which produced 32 [[ampere|amps]] instead of the 25A of the original (70-11073)

The fourth option is the 'communication regulator', 54-13764, which provides +15V/-15V.

The models are:

{| class="wikitable"
! Model !! Input !! Regulators
|-
| -AA || 115 || 25A +5V, MOS and core
|-
| -AB || 230 || 25A +5V, MOS and core
|-
| -BA || 115 || 25A +5V, MOS only
|-
| -BB || 230 || 25A +5V, MOS only
|-
| -CA || 115 || 32A +5V, MOS and core
|-
| -CB || 230 || 32A +5V, MOS and core
|-
| -DA || 115 || 32A +5V, MOS only
|-
| -DB || 230 || 32A +5V, MOS only
|-
| -UA || 115 || 32A +5V, MOS, communication
|-
| -UB || 230 || 32A +5V, MOS, communication
|}

The H777 does not use a [[power harness]]; rather, it has a 'power distribution board' built into one end panel, which holds the usual [[DEC power distribution connectors]]; the [[backplane]](s) mounted in the BA11-L plug in there.

The power distribution board also holds a connector for the usual DEC [[Remote Switching Control Bus]]; this could be used either as an output (on boxes which contained a front panel) or an input (for boxes used as expansion boxes).

It was mounted longitudinally, at one side of mounting box, and included its own cooling fan.

==External links==

* [http://bitsavers.org/pdf/dec/unibus/BA11-L/EK-BA11L-TM-001_Oct77.pdf BA11-L mounting box technical manual] (EK-BA11L-TM-001) - the H777 is covered on pp. 14-19 and Chapter 3, pp. 36-80
* [http://www.bitsavers.org/pdf/dec/pdp11/1124/EK-11024-TM-001_PDP11_24_System_Technical_Manual_Jun81.pdf PDP-11/24 System Technical Manual] - covers the communication regulator in Appendix A
* [http://bitsavers.org/pdf/dec/pdp11/1104/MP00019_1104_EngrDrws_Feb78.pdf 11/04 Engineering Drawings] - H777-0 Vol. 1 Field Maintenance Print Set (MP00016) is on pp. 104-142
* [http://www.bitsavers.org/pdf/dec/pdp11/1124/MP01018_Rev_F_11-24_Engineering_Drawings_Mar84.pdf 11/24 Field Maintenance Print Set] - H777-0 Vol. 2 Field Maintenance Print Set (MP00309) is on pp. 169-194

[[Category: DEC Power Supplies]]

DR11-B parallel interface

2026-10-06T08:41:21Z

Jnc: /* External links */ Bitsavers has reorganized a bit

The '''DR11-B''' was a [[parallel interface]] for the [[UNIBUS]], one which used [[Direct Memory Access|DMA]] to transfer data to a user device.

The interface between the DR11-B and the user device uses a number of unidirectional control lines (below), which control data transfer; and sets of three 'status' and 'control' lines, which appear in the Status and Command Register. By appropriate manipulation of the control lines, the user device can do byte or word cycles on the bus, perform read-modify-write bus cycles, or do block 'burst' bus transfers.

Data going to the user device is [[buffer]]ed in a set of [[latch]]es; data coming from the user device is ''not'' buffered, and must be held valid for the duration of the resultant bus cycle.

==Registers==

{| border=1
! Register !! Abbreviation !! Address
|-
|Word Count Register || DRWC || 772410
|-
|Bus Address Register || DRBA || 772412
|-
|Status and Command Register || DRST || 772414
|-
|Data Buffer Register || DRDB || 772416
|}

The [[address]]es shown are for the first DR11-B in a system; additional ones are normally set to be at 772430, 772450, 772470, etc.

===772410: Word Count Register (DRWC)===
{{16bit-header}}
| colspan=16 | WC15 <---> WC00
{{16bit-bitout}}

===772412: Bus Address Register (DRBA)===
{{16bit-header}}
| colspan=16 | BA15 <---> BA00
{{16bit-bitout}}

===772414: Status and Command Register (DRST)===
{{16bit-header}}
| ERROR || NEX || ATTN || MAINT || colspan=3 | DSTAT A-C || CYCLE || READY || IE || colspan=2 | XBA16-17 || colspan=3 | FNCT1-3 || GO
{{16bit-bitout}}

===772416: Data Buffer Register (DRDB)===
{{16bit-header}}
| colspan=16 | Data15 <---> Data00
{{16bit-bitout}}

Note: Unlike most DEC DMA devices, an overflow in the Bus Address Register does not carry into the Extended Memory bits in the CSR.

==User Device Interface==

===User Input Signals===

{| class="wikitable"
! Signal Name !! Count !! Function
|-
| DAT IN || 16 || Data from user device
|-
| CONTROL || 2 || Specify type of UNIBUS cycle (DATI, etc)
|-
| CYCLE REQ || 2 || Either one can set the CYCLE bit, which causes a bus cycle
|-
| WC INC ENB || 1 || Word Count Increment Enable
|-
| BA INC ENB || 1 || Bus Address Increment Enable
|-
| A00 || 1 || Bus Address Bit 0
|-
| DSTAT || 3 || Device Status Bits
|-
| ATTN || 1 || Attention bit in the DRST
|-
| SINGLE CYCLE || 1 || Controls use of burst mode for bus cycles
|}

===User Output Signals===

{| class="wikitable"
! Signal Name !! Count !! Function
|-
| DAT OUT || 16 || Data to user device
|-
| INITIALIZE || 1 || UNIBUS INIT or interlock error
|-
| FNCT || 3 || Function bits in the DRST
|-
| READY || 1 || READY bit from the DRST
|-
| BUSY || 1 || Bus cycle in progress
|-
| END CYCLE || 1 || Bus cycle is complete
|-
| GO || 1 || GO bit from the DRST
|}

==Implementation==

It was constructed from a number of smaller [[FLIP CHIP]]s which were installed in custom 4-slot [[system unit]] [[backplane]].

The extant DR11-B documentation does not show either the modules used in the DR11-B, or their locations in the backplane, so that information is given here.

The modules are:

* M112 - 10 x 2-input NOR gates
* M113 - 10 x 2-input NAND gates
* M116 - 6 x 4-input NOR gates
* M205 - 5 x 'D' [[flip-flop]]s
* 2 x M208 - 8-bit buffer / shift-register
* M239 - 3 x 4-bit counter/register
* 2 x M611 - High speed power inverters
* M796 - UNIBUS Master Control
* [[M782 Interrupt Control|M7821]] - [[Interrupt]] Control
* M7219 - Bus Interface

The M7219 is a [[DEC card form factor|quad]] card; the others are all single. (Of those, the M796 and M7821 are [[DEC card form factor|extended length]]; the others are all standard length.) The M239 is used to hold the Command and Status Register.

Board locations (as seen from the board insertion side of the backplane, not the [[wire-wrap]] pin side, as is common in [[DEC]] documentation) are:

{| class="wikitable"
! !! colspan="6" | Connector
|-
! Slot !! A !! B !! C !! D !! E !! F
|-
| 1 || colspan="2" style="text-align:center;" | UNIBUS In || colspan="4" style="text-align:center;" | M7219
|-
| 2 || colspan="2" style="text-align:center;" | Test board || M208 || M208 || M7821 || M796
|-
| 3 || Power || M205 || M611 || M611 || M112 || M113
|-
| 4 || colspan="2" style="text-align:center;" | UNIBUS Out || colspan="2" | User connector || M116 || M239
|}

Connection to the user device is via either a pair of M957 Split-Lug Cable boards, or via an M9760 (dual) Twisted Pair Cable Connector board. The M9680 (dual) board is a loopback test board, which can be inserted in place of the user connection board(s).

Power comes in on a single-width stub card in the A3 slot (as is canonical in the [[PDP-11/20]] generation of [[PDP-11]]s).

==Further reading==

* ''DRll-B Engineering Drawings'' - not online at this time

==External links==

* [http://www.bitsavers.org/www.computer.museum.uq.edu.au/pdf/DEC-11-HDRBA-D-D%20DR11-B&DA11-B%20Manual.pdf DR11-B/DA11-B manual] (DEC-11-HDRBA-D-D)
* [http://www.bitsavers.org/pdf/dec/unibus/DR11-B/EK-DR11B-TM-004_DR11-B_DA11-B_Manual_Sep74.pdf DR11-B/DA11-B manual] (EK-DR11B-TM-004)

[[Category: UNIBUS Parallel Interfaces]]

DA11-B DMA UNIBUS Link

2026-10-06T08:35:55Z

Jnc: /* External links */ Bitsavers has reorganized a bit

The '''DA11-B DMA UNIBUS Link''' allows two [[UNIBUS]]es to be directly connected; either single words, or blocks of up to 32K words, can be transferred. The channel is [[half-duplex]]. Although the DA11-B can ''generate'' [[interrupt]]s on either UNIBUS (in response to user commands given directly to it via its Control and Status Register), it cannot ''transfer'' interrupts (i.e. from one UNIBUS to the other).

In Block Mode, the DA11-B uses [[Direct Memory Access|DMA]] on the source bus to read words in the block, and then uses DMA on the other UNIBUS to write the data.

The DA11-B was produced by [[Digital Equipment Corporation|DEC]]'s Computer Special System division; it was built out of a pair of [[DR11-B parallel interface]]s, each taking a [[system unit]] [[backplane]] in each computer. An M7229 buffer module is installed in each DR11-B's user connection slot, [[DEC edge connector contact identification|CD0]].

==Registers==

{| border=1
! Register !! Address
|-
|Word count Register || XXXX00
|-
|Bus Address Register || XXXX02
|-
|Control and Status Register || XXXX04
|-
|Data Buffer Register || XXXX06
|}

The first DA11-B in a system is usually assigned register addresses starting with 0772410.

{{semi-stub}}
==External links==

* [http://www.bitsavers.org/pdf/dec/unibus/DA11-B/2M-0C75A-00_DA11B.pdf DA11-B PDP-11 Interprocessor Link]
* [http://www.bitsavers.org/pdf/dec/unibus/DR11-B/EK-DR11B-TM-004_DR11-B_DA11-B_Manual_Sep74.pdf DR11-B/DA11-B manual] (EK-DR11B-TM-004) - the DA11-B is covered in Appendix C
* [http://www.bitsavers.org/pdf/dec/pdp11/handbooks/PDP-11_PeripheralsHbk_1976.pdf pdp11 peripherals handbook] - the DA11-B is covered on pp. 83-87

[[Category: UNIBUS Machine Interfaces]]

DH11 asynchronous serial line interface

2026-10-06T08:27:05Z

Jnc: /* External links */ Bitsavers has reorganized a bit

The '''DH11 asynchronous serial line interface''' is a [[UNIBUS]] [[peripheral]] which provides up to 16 [[asynchronous serial line]]s. Output used [[Direct Memory Access|DMA]] (with each line having its own [[buffer]] [[pointer]] and count); on input a 64-character [[First-In First-Out buffer|FIFO buffer]] made over-runs unlikely.

As a UNIBUS device, it was usable on the [[PDP-11]] and [[VAX]] computers. Although it first appeared very early on in the lifetime of the PDP-11, it was extremely powerful and flexible, and remained an option for a very long time.

The parameters for each line:

* separate input and output baud rates
* character length (5-8 bits)
* stop bits (1, 1-1/2 and 2)
* parity (odd, even, none)

could be set dynamically (unlike, for example, the [[DJ11 asynchronous serial line interface|DJ11]], which set parameters for groups of lines using [[jumper]]s)

Fourteen supported [[baud rate]]s ranged from 50 to 9600, along with 0 (to disable a line); two additional speeds were available with optional [[clock]] [[FLIP CHIP]]s. A 'break' condition on the line (i.e. continuous assertion) could also be generated and detected.

For [[modem]] control, a single [[DM11-BB Modem Control Option‎]] per DH11, mounted in the main DH11 [[backplane]] along with the rest of the DH11 cards, was required. (The DM11-BB is logically a separate device, albeit one housed in the DH11.)

==Device registers==

The [[register]]s LPR through BCR are replicated, with one for each line in the device; the 'Line' field in the SCR indicates which one is currently available.

{| border=1
! Register !! Abbreviation !! Address
|-
|System Control Register || DHSCR || 760020
|-
|Next Received Character Register || DHNRCR || 760022
|-
|Line Parameter Register || DHLPR || 760024
|-
|Current Address Register || DHCAR || 760026
|-
|Byte Count Register || DHBCR || 760030
|-
|Buffer Active Register || DHBAR || 760032
|-
|Break Control Register || DHBRCR || 760034
|-
|Silo Status Register || DHSSR || 760036
|}

The [[address]]es shown are for the first DH11 in a system; additional ones are normally set to be at 760040, 760060.

===760020: System Control Register (DHSCR)===
{{16bit-header}}
| TI || SI || OIE || SIE || MCLR || NXM || MAINT || CNXM || RI || RIE || colspan=2 | MEX || colspan=4 | Line
{{16bitoctal-bitout}}

===760022: Next Received Character Register (DHNRCR)===
{{16bit-header}}
| DPR || OVR || FRM || PAR || colspan=4 | Line || colspan=8 | Data
{{16bitoctal-bitout}}

===760024: Line Parameter Register (DHLPR)===
{{16bit-header}}
| Echo || HFD || colspan=4 | TSpeed || colspan=4 | RSpeed || ODD || PAR || Unused || 2SB || colspan=2 | Length
{{16bitoctal-bitout}}

===760036: Silo Status Register (DHSSR)===
{{16bit-header}}
| Rsvd || Unused || colspan=6 | Fill || colspan=2 | XMem || colspan=6 | Alarm
{{16bitoctal-bitout}}

==Initial implementation==

The original implementation took an entire double [[system unit]] [[backplane]], containing multiple cards (see list below). It came in 'earlier' and 'later' versions.

In the 'early' versions, modular 'line conditioning' units allowed support of either [[20mA current loop serial line interface|20mA]] or [[EIA RS-232 serial line interface|EIA RS-232]] serial lines; these were installed in a separate rack-mounted [[DEC card form factor|dual-height]] [[DM11 distribution panel]] [[backplane]] (which required its own independent [[power supply]]).

[[Image:H317BUncovered.jpg|thumb|right|300px|H317-B with cover off]]

In the 'later' units, to reduce the cost, line conditioning was performed on boards mounted in the main DH11 backplane, and a rack-mounted passive H317-B distribution panel provided connectors for individual lines.

These 'later' versions only supported EIA-type line conditioning (with or without modem control); to add modem control, a different implementation of the DM11-BB was required (one which did the EIA level conversion on the control lines internally).

===Versions===

The 'early' versions of the DH11 were:

* DH11-AA - Basic unit (110VAC), requires line conditioning units in addition
* DH11-AB - Telegraph line version (see below)
* DH11-AC - Basic unit (220VAC), requires line conditioning units in addition

The 'later' versions were:

* DH11-AD - EIA level conversion, modem control
* DH11-AE - EIA level conversion, no modem control

For the telegraph line option, the line conditioning backplane and its power supply were omitted, and up to two DH11's were connected to a DC08CS Telegraph Converter Panel.

===Main unit===

[[Image:M791.jpg|300px|thumb|right|M791 connector card]]

The 'basic' DH11 included the following [[DEC card form factor|hex-width]] boards:

* M7277 - Transmit scanner
* M7278 - Registers and byte count
* M7288 - Line parameters control
* M7289 - Receiver scanner

a dual-width and two quads:

* M7279 - FIFO buffer
* M7280 (2) - Octal [[Universal Asynchronous Receiver/Transmitter|UART]]s

and a number of single-width cards:

* M4540 - Crystal clock
* M7360 - Priority selector
* M796 - UNIBUS master control
* [[M782 Interrupt Control‎|M7821]] (2) - Interrupt control (transmit. receive, and [[Non-Processor Request|NPR]])
* M405 - Baud clock (optional; 2)
* M791 - [[Berg connector]] header connector card

Board locations (as seen from the board insertion side of the backplane, not the [[wire-wrap]] pin side, as is common in [[DEC]] documentation) are:

{| class="wikitable"
! !! colspan="6" | Connector
|-
! Slot !! A !! B !! C !! D !! E !! F
|-
| 1 || colspan="2" style="text-align:center;" | UNIBUS In || colspan="4" style="text-align:center;" | Reserved for DM11-BB
|-
| 2 || M7821 || M796 || colspan="4" style="text-align:center;" | Reserved for DM11-BB
|-
| 3 || colspan="6" style="text-align:center;" | M7278
|-
| 4 || colspan="6" style="text-align:center;" | M7277
|-
| 5 || colspan="6" style="text-align:center;" | M7289
|-
| 6 || M7821 || M405 (optional) || colspan="4" style="text-align:center;" | M7280
|-
| 7 || M7360 || M971 (cable) || colspan="4" style="text-align:center;" | M7280
|-
| 8 || colspan="6" style="text-align:center;" | M7288
|-
| 9 || colspan="2" style="text-align:center;" | UNIBUS Out || colspan="2" style="text-align:center;" | M7279 || M405 (optional) || M4540
|}

An optional M794 maintenance card could be plugged into the slot normally used by the M971, for testing.

The 'later' versions of the DH11 both included:

* M5906 EIA conversion module

which occupied a dual slot (used by an M7360 Priority Selector card and an M971 Cable Connector card, used to connect the DH11 to the line conditioning units, in the 'early' versions).

The -AD version, which included a 'later' DM11-BB for modem control, also used:

* M7807 - Mux and Bus Control
* M7808 - Mux and Modem Scan Control

These boards fitted into the same slots occupied by the DM11-BB boards in the 'early' versions (the M7807 in slot 1, the M7808 in slot 2).

===Distribution panels===

The rack-mounted passive distribution panel initially used in the 'later' versions was the H317-B passive distribution panel, initially created for the DJ11, which mounted directly into a standard 19" rack, and contained 16 DB-25P connectors.

It was connected to the DH11 with a pair of BC08S cables, which carried the 'main' signals (data, etc - i.e. non-modem control); these cables were thus required for both 'later' versions. For the modem control signals (Carrier Detect, etc) used with the DH11-AD, four BC08R cables were used.

[[Image:H3007Panel.jpg|thumb|right|200px|H3007]]

Later, the H3007 8-line EIA distribution panel, designed for use in later DEC cabinets with improved EMI [[interference]] characteristics, was introduced; the H3007 fits into the standard panel 21cm x 10cm cutout found in these systems.

==Design flaw==

Some time after it was introduced, it became apparent that there was a design flaw associated with the 'silo alarm' functionality. This mechanism allowed increased processing efficiency by allowing multiple input characters to be processed with a single [[interrupt]]; it involved a register (the 'Silo Alarm Level') which contained a count of the number of characters required in the input buffer (the 'silo') before an interrupt was generated.

The problem is that if less characters than that arrive, and then no more, an interrupt is never generated. So, code which uses higher levels for the silo alarm has to periodically check to see if less characters than that have arrived, and are waiting.

(Apparently, the designer admitted that this was a flaw; he indicated that there should have been a timer, such that after the first character entered the silo, if the silo was still non-empty after the timer ran out, an interrupt would be generated.)

==Later implementations==

The DH11 was later re-implemented as the [[DHU11 asynchronous serial line interface|DHU11]], which was not programmatically identical to the DH11, but had the same capabilities. (It also had the input timer, discussed above.) It fitted on a single [[DEC card form factor|hex-height]] card, which plugged into a [[Modified UNIBUS Device|MUD]] slot.

For the [[QBUS]], the [[DHV11 asynchronous serial line interface|DHV11]] and [[DHQ11 asynchronous serial line interface|DHQ11]] (the former was mostly programmatically identical to the DHU11; the latter could be set to exactly emulate either a DHU11 or a DHV11) appeared; they only supported 8 lines each (via two quad breakout panels), however.

==External links==

* [http://www.bitsavers.org/pdf/dec/unibus/DH11/EK-ODH11-OP-002_DH11_Asynchronous_16-line_Multiplexer_Users_Manual_Sep76.pdf DH11 asynchronous 16-line multiplexer user's manual] (EK-ODH11-OP-002)
* [http://www.bitsavers.org/pdf/dec/unibus/DH11/EK-0DH11-MM-003_Apr75.pdf DH11 asynchronous 16-line multiplexer maintenance manual] (EK-ODH11-MM-003)
* [http://www.bitsavers.org/pdf/dec/unibus/DH11/DH11_EngrDrws_Jul76.pdf DH11 Engineering Drawings]
* [http://woffordwitch.com/McNamaraDH11.asp The Development Of The DH11 Multiplexer]

[[Category: UNIBUS Asynchronous Serial Interfaces]]

DM11 Asynchronous 16-line Single-Speed Multiplexer

2026-10-06T08:10:38Z

Jnc: /* External links */ Bitsavers has reorganized a bit; has a doc err

The '''DM11 Asynchronous 16-Line, Single-Speed Multiplexer''' (formally, the '''DM11-AA''') was a very early [[UNIBUS]] [[peripheral]] which provided up to 16 [[asynchronous serial line]] connections. It was in some sense a predecessor to the [[DH11 asynchronous serial line interface|DH11]], in that it used [[Direct Memory Access|DMA]].

However, unlike any other UNIBUS peripheral, much of its internal state was actually stored in [[main memory]], not in [[register]]s in the device itself (not even in ones not directly accessible from the UNIBUS); DMA was used to gain access to it. (Perhaps this was early enough in time that [[gate]]s for [[flip-flop]]s for registers were too expensive, or took too much space on the [[printed circuit board|board]].)

The data stored in memory included:

* per-line current output [[buffer]] [[address]]
* per-line current output transfer length
* per-line input [[shift register]]s
* input buffer (a shared, circular [[First-In First-Out buffer|FIFO buffer]])

(The 'input shift registers' were needed because [[Universal Asynchronous Receiver/Transmitter|UART]] [[integrated circuit|chips]] did not exist yet. The [[sampling]] of the incoming serial data stream, and the conversion to [[parallel]] form, was done in discrete [[logic]].)

There were separate receive and transmit [[interrupt]]s, and [[half-duplex]] and [[full-duplex]] operation are supported in [[hardware]]. The 64-[[character]] FIFO buffer made input over-runs unlikely.

The line parameters:

* [[baud rate]]s (ranging from 45 to 1200)
* character length (5-8 bits)
* output stop bits (1 or 2)

were the same for all lines, and set by [[jumper]]s; [[parity]] was computed on incoming data. A 'break' condition on the line (i.e. continuous assertion) could also be generated and detected.

==Implementation==

The implementation of the basic DM11-AA used a custom double [[system unit]] [[backplane]], containing multiple cards; a [[flat cable]] connected this to separate rack-mounted [[DEC card form factor|dual-height]] [[DM11 distribution panel]] backplane (which required its own independent [[power supply]]).

Modular 'line conditioning' units from the [[DF11 Communications Line Adapter]] series were installed in the distribution panel to allow support of either [[20mA current loop serial line interface|20mA]] or [[EIA RS-232 serial line interface|EIA RS-232]] serial lines. The alternative DC08CS distribution panel allowed connection to telegraph and Telex lines.

Lines could be connected to [[modem]]s, provided the correct line conditioning units were installed, but modem control required a [[DM11-BB Modem Control Option]], mounted in the main DM11 backplane along with the rest of the DM11-AA cards, and connected to the distribution panel via other flat cables which carried the modem control signals. The DM11-BB is logically a separate device from the DM11-AA, albeit one housed in the same DM11 backplane.

==DM11-AA Device registers==

{| border=1
! Register !! Abbreviation !! Address
|-
|Status Register || DMCSR || 775000
|-
|Buffer Active Register || DMBAR || 775002
|-
|Break Status Register || DMBSR || 775004
|-
|Base Address Register || DMBADR || 775006
|}

The Buffer Active Register has one bit per line to indicate that has output pending (described by the Current Address and Word Count tables below); the Break Status Register also has one bit per line. The Base Address Register is 8 bits wide, so the in-memory tables must start on a 0400 boundary.

The addresses shown are for the first DM11-AA11 in a system; additional ones (up to 16 total) are normally set to be at 775010, 775020, etc to 775170.

===775000: Status Register (DMCSR)===
{{16bit-header}}
| TINT || TO || SOVR || TIE || colspan=4 | Unused || DONE || RIE || colspan=2 | MEMEX || Unused || MAINT || FHD || RENB
{{16bitoctal-bitout}}

*TINT - Transmit Interrupt
*TO - Timeout; non-existent memory referenced
*SOVR - System Overrun; bus access not gained in time
*TIE - Transmit Interrupt Enable
*DONE - Done; input character placed in the Circular Buffer
*RIE - Receiver Interrupt Enable
*MEMEX - Memory Extension
*MAINT - Maintenance Bit; connects line 0 (only) receiver directly to transmitter
*FHD - Full/Half Duplex Select; disables receivers on lines that are transmitting
*RENB - Receiver Enable

==Memory tables==

The four tables of per-line data kept in main memory were:

{| border=1
! Table !! Offset (in [[byte]]s) !! Size (in bytes)
|-
|Current Address || 0 || 32
|-
|Word Count || 040 || 32
|-
|Bit Assembly || 0100 || 32
|-
|Circular Buffer || 0200 || 128
|}

The first two are for transmitting, and defined the output buffer; the last two for receiving. The format of the entries in the input buffer is:
{{16bit-header}}
| Valid || Break || Parity || colspan="4" | Channel || Unused || colspan="8" style="text-align:center;" | Character
{{16bitoctal-bitout}}

The input character, which may be less than 8 bits wide, is stored right-justified.

==Implementation==

The DM11-AA boards (all [[DEC card form factor|quad]], except for the Control C, which is a dual) which plugged into the DM11 backplane are:

* M7240 - Control A
* M7241 - Control B
* M7242 - Control C
* M7243 - Transmitter D
* M7244 - Transmitter E
* M7245 - Receiver

and 4 single-width, non-DM11-specific cards:

* [[M782 Interrupt Control‎|M782]] - Interrupt control (two)
* [[M105 Address Selector|M105]] - Address selection
* M405 - Clock

Board locations (as seen from the board insertion side of the backplane, not the [[wire-wrap]] pin side, as is common in [[DEC]] documentation) are:

{| class="wikitable"
! !! colspan="6" | Connector
|-
! Slot !! A !! B !! C !! D !! E !! F
|-
| 1 || colspan="2" style="text-align:center;" | UNIBUS In || colspan="4" style="text-align:center;" | M7240
|-
| 2 || || M105 || colspan="4" style="text-align:center;" | M7241
|-
| 3 || Power|| M405 || M782 || M782 || colspan="2" style="text-align:center;" | M7242
|-
| 4 || || M974 Cable || colspan="4" style="text-align:center;" | M7245
|-
| 1 || colspan="2" |   || colspan="4" style="text-align:center;" | M7244
|-
| 2 || colspan="2" |   || colspan="4" style="text-align:center;" | M7243
|-
| 3 || Power || || colspan="4" style="text-align:center;" | Reserved for DM11-BB
|-
| 4 || colspan="2" style="text-align:center;" | UNIBUS Out || colspan="4" style="text-align:center;" | Reserved for DM11-BB
|}

('''''NOTE''''': ''The diagram which is the source for this table has two different cards marked as 'M7245', and no 'M7243's. So it clearly has errors; the M7243 is referred to elsewhere as the transmitter card, and the M7245 as the receiver, so the numbers are correct, but the locations might be swapped.'')

Power comes in on a single-width stub card in the A3 slots (as is canonical in the [[PDP-11/20]] generation of [[PDP-11]]s).

==Further reading==

* ''DM11 asynchronous 16-line single-speed multiplexer manual'' (DEC-11-HDMA-D, EK-DM11A-TM-002) - latter is available in fiche, but neither is online
* ''DM11 Asynchronous 16-Line Single-Speed Multiplexer Engineering Drawing Manual'' - not available online
* ''DM11-BB Modem Control Option Engineering Drawings'' - not available online

==External links==

* [http://www.bitsavers.org/www.computer.museum.uq.edu.au/pdf/DEC-11-HDMBA-A-D%20DM11-BB%20Modem%20Control%20Option%20Manual.pdf DM11-BB modem control option manual], (DEC-11-HDMBA-A-D) pp. 1-5
* [http://www.bitsavers.org/pdf/dec/pdp11/handbooks/PDP-11_PeripheralsHbk_1972.pdf pdp11 peripherals and interfacing handbook (1972 edition)] - the DM11 is covered on pp. 141-160 of the PDF

[[Category: UNIBUS Asynchronous Serial Interfaces]]
[[Category: DEC Documentation Errors]]

DM11-BB Modem Control Option

2026-10-06T08:04:40Z

Jnc: /* External links */ Bitsavers has reorganized a bit

[[Image:DM11-BBM7807.jpg|thumb|right|250px|M7807 Mux and Bus Control card of 'later' DM11-BB]]

The '''DM11-BB Modem Control Option''' worked with several early [[UNIBUS]] [[asynchronous serial line]] [[peripheral]]s to allow the lines to be connected to [[modem]]s. It could be set to [[interrupt]] the [[Central Processing Unit|CPU]] when a modem control line (Ring, Carrier, etc) changed state.

The DM11-BB is logically a separate device from the serial line interfaces, albeit one housed in the same [[backplane]]. It was used with the [[DM11 asynchronous serial line interface|DM11]] and [[DH11 asynchronous serial line interface|DH11]] interfaces. Both of these interfaces themselves used a custom [[system unit]] backplane, containing multiple cards; [[flat cable]]s connected this to a separate 5-1/4" high rack-mounted [[DEC card form factor|dual-height]] [[distribution panel]].

There were two different versions of the DM11-BB (unfortunately, there is no accepted naming system for them). The DM11 and early models of the DH11 used the 'early version' of the DM11-BB; it used an 'active' (powered) [[DM11 distribution panel]] backplane. Modular 'line conditioning' units were plugged into the distribution panel backplane to allow support of [[EIA RS-232 serial line interface|EIA RS-232]] serial lines connected to modems.

Later DH11s used the 'new version' of the DM11-BB, which was [[program compatible]] with the early version, but included built-in EIA level conversion, allowing the use of a passive (un-powered) H317-B distribution panel.

==DM11-BB Device registers==

{| border=1
! Register !! Abbreviation !! Address
|-
|Control and Status Register || DMCSR || 770500
|-
|Line Status Register || DMLSR || 770502
|}

The addresses shown are for the first DM11-BB in a system; additional ones (up to 16 total) are normally set to be at 770504, 770510, etc to 770674. It used one [[interrupt vector]], allocated from the [[floating device vectors]].

===770500: Control and Status Register (DMCSR)===
{{16bit-header}}
| RING || CARR || CTS || SREC || CLRSC || CLRMUX || MAINT || STEP || DONE || IE || SCEN || Unused || colspan=4 | Line
{{16bitoctal-bitout}}

*RING - Ring Flag; transition detected
*CARR - Carrier Flag; transition detected
*CTS - Clear to Send Flag; transition detected
*SREC - Secondary Receive Flag; transition detected
*CLRSC - Clear Scanner
*CLRMUX - Clear Multiplexer
*MAINT - Maintenance Mode
*STEP - Step; increment scan line number
*DONE - Done; scan detected a transition, scan halted
*IE - Interrupt Enable
*SCEN - Scan Enable
*Line - Line Number

===770502: Line Status Register (DMLSR)===
{{16bit-header}}
| colspan=8 | Unused || RING || CARR || CTS || SREC || STX || RTS || DTR || LEN
{{16bitoctal-bitout}}

*RING - Ring; current status of Ring lead
*CARR - Carrier; current status of Carrier lead
*CTS - Clear to Send; current status of Clear to Send lead
*SREC - Secondary Receive; current status of Secondary Receive lead
*STX - Secondary Transmit; set Secondary Transmit lead
*RTS - Ready to Send; allow modem to transmit
*DTR - Data Terminal Ready; allow modem to enter data mode
*LEN - Line Enable

==Implementation==

[[Image:DM11-BBM7808.jpg|thumb|left|250px|M7808 Mux and Modem Scan Control card of 'later' DM11-BB]]

The early version of the DM11-BB was connected to the DM11 distribution panel via flat cables which carried the modem control signals, which ran from the M7247 card (two per card) to [[DEC card form factor|single-width]] M971 cards which plugged into the backplane of the DM11 distribution panel (one for each group of 4 lines). The DM11-BB boards (all dual-width) were:

* M7246 - Scan
* M7247 - Data Mux (two)

and 2 single-width, non-DM11-specific cards:

* [[M782 Interrupt Control|M7820]] - Interrupt control
* [[M105 Address Selector|M105]] - Address selection
<br clear=all>

===DM11 board locations===

Board locations in the DM11 backplane (as seen from the board insertion side of the backplane, not the [[wire-wrap]] pin side, as is common in [[DEC]] documentation) were:

{| class="wikitable"
! !! colspan="6" | Connector
|-
! Slot !! A !! B !! C !! D !! E !! F
|-
| 1 || colspan="2" style="text-align:center;" | UNIBUS In || colspan="4" style="text-align:center;" | M7240
|-
| 2 || || M105 || colspan="4" style="text-align:center;" | M7241
|-
| 3 || Power|| M405 || M782 || M782 || colspan="2" style="text-align:center;" | M7242
|-
| 4 || || M974 Cable || colspan="4" style="text-align:center;" | M7245
|-
| 1 || colspan="2" |   || colspan="4" style="text-align:center;" | M7244
|-
| 2 || colspan="2" |   || colspan="4" style="text-align:center;" | M7243
|-
| 3 || Power || || colspan="2" | M7247 || colspan="2" | M7246
|-
| 4 || colspan="2" style="text-align:center;" | UNIBUS Out || colspan="2" | M7247 || M105 || M7820
|}

(DM11-BB boards were in the last two slots.)

===Early DH11 board locations===

{| class="wikitable"
! !! colspan="6" | Connector
|-
! Slot !! A !! B !! C !! D !! E !! F
|-
| 1 || colspan="2" style="text-align:center;" | UNIBUS In || colspan="2" | M7247 || M105 || M7821
|-
| 2 || M7821 || M796 || colspan="2" | M7247 || colspan="2" style="text-align:center;" | M7246
|-
| 3 || colspan="6" style="text-align:center;" | M7278
|-
| 4 || colspan="6" style="text-align:center;" | M7277
|-
| 5 || colspan="6" style="text-align:center;" | M7289
|-
| 6 || M7821 || M405 || colspan="4" style="text-align:center;" | M7280
|-
| 7 || M7360 || M971 || colspan="4" style="text-align:center;" | M7280
|-
| 8 || colspan="6" style="text-align:center;" | M7288
|-
| 9 || colspan="2" style="text-align:center;" | UNIBUS Out || colspan="2" style="text-align:center;" | M7279 || M405 || M4540
|}

(DM11-BB boards were in the first two slots.)

===Later DM11-BB implementation===

[[Image:H317BUncovered.jpg|thumb|right|250px|H317-B passive distribution panel with cover off]]

The 'later' DM11-BB used two new quad-width boards (the DH11 backplane, etc, were otherwise identical):

* M7807 - Mux and Bus Control
* M7808 - Mux and Modem Scan Control

These boards fitted into the same slots occupied by the DM11-BB boards in the 'early' DH11 versions - the M7807 in slot 1, the M7808 in slot 2. Two flat cables ran from each to the passive distribution panel.

==See also==

* [[DM11-BA Modem Control Multiplexor]]

==Further reading==

* ''DM11-BB Modem Control Option Engineering Drawings'' (not available online)

==External links==

* [http://www.bitsavers.org/www.computer.museum.uq.edu.au/pdf/DEC-11-HDMBA-A-D%20DM11-BB%20Modem%20Control%20Option%20Manual.pdf DEC-11-HDMBA-A-D DM11-BB modem control option manual]
* [http://www.bitsavers.org/pdf/dec/unibus/DH11/DH11_EngrDrws_Jul76.pdf DH11 Engineering Drawings] - contains some early DM11-BB engineering drawings on pp. 98-125; late DM11-BB on pp. 165-178

[[Category: UNIBUS Asynchronous Serial Interfaces]]

DHU11 asynchronous serial line interface

2026-10-05T19:25:04Z

Jnc: /* External links */ Bitsavers has reorganized a bit

[[Image:DHU11.jpg|350px|thumb|right|DHU11 M3105 board]]

The '''DHU11 asynchronous serial line interface''' was a replacement for the [[UNIBUS]] [[DH11 asynchronous serial line interface|DH11]]. It was not programmatically exactly identical to the DH11, but had all the same basic capabilities: it provided 16 [[EIA RS-232 serial line interface|RS-232]] [[asynchronous serial line]]s, and used [[Direct Memory Access|DMA]] on the output side.

The reasons for the replacement of the DH11 are not known, but likely the major one was cost: the DH11 consisted of an entire double [[system unit]] [[backplane]], containing multiple cards; the DHU11 was a single card. It had some minor improvements over the DH11 (including a fix for its [[DH11 asynchronous serial line interface#Design flaw|silo problem]]), but they seem not significant enough by themselves to warrant its replacement. They included:

* input used a 256-character [[First-In First-Out buffer|FIFO buffer]] (somewhat larger than the original DH11's 64-character one);
* the DHU11 includes several [[microprocessor]]s, and has extended capabilities, including a [[diagnostic]] self-test, and [[flow control]] support;
* the DHU11 has the ability to transmit under program control; each line has a 64-character FIFO output buffer.

==Implementation==

[[Image:H3029DHU11Dist.jpg|250px|thumb|left|H3029 Distribution Panel]]

Physically, the DHU11 consisted of a single [[DEC card form factor|hex]] card, the M3105, which plugged into a [[Modified UNIBUS Device|MUD]] slot. It connected to a pair of H3029 distribution panels (8 lines each) via BC05L [[flat cable]]s, two per distribution panel; the BC05L connects to a 40-pin [[Berg connector|Berg header]] on each end. The H3029 contains eight male [[EIA RS-232 serial line interface#Connectors|DB-25 connectors]] (DB-25P).

==Device registers==

The [[register]]s in the DHU11 are somewhat different from those in the DH11:

* it was intended to be [[program compatible]] with its [[QBUS]] equivalents (the [[DHV11 asynchronous serial line interface|DHV11]]; and later the [[DHQ11 asynchronous serial line interface|DHQ11]], which could be set to exactly emulate the DHU11), and since the QBUS has a larger [[address space]] than the UNIBUS, it needed two [[word]]-sized registers to hold the output buffer [[address]];
* the previously mentioned improvements.

{| border=1
! Register !! Abbreviation !! Address
|-
|Control and Status Register || CSR || 760020
|-
|Receive Buffer Register || RBUF || 760022
|-
|Receive Timer Register* || RXT || 760022
|-
|Line Parameter Register || LPR || 760024
|-
|Transmit FIFO Data Register || TFD || 760026
|-
|Transmit FIFO Size Register* || TFS || 760026
|-
|Line Status Register* || STAT || 760027
|-
|Line Control Register || CTRL || 760030
|-
|Transmit Buffer Address Register Low || TBADL || 760032
|-
|Transmit Buffer Address Register Hi || TBADH || 760034
|-
|Transmit Buffer Count Register || TBCT || 760036
|}

Registers marked with a '*' are byte width; the others are all word-width. The RBUF and RXT share an address, as do the TFD and TFS: the RBUF is read only, and the RXT is write only; the TFD is write only, and the TFS and STAT are read only. The LPR through TBCT are replicated, with one for each line in the device; the 'Line' field in the CSR indicates which one is currently available.

The [[address]]es shown are for the first DHU11 in a system; additional ones are normally set to be at 760040, 760060, etc.

===Control and Status Register (CSR)===
{{16bit-header}}
| TXA || TXIE || DF || TDE || colspan=4 | Tx Line || RDA || RXIE || MR || SKIP || colspan=4 | Line
{{16bitoctal-bitout}}

*TXA - Transmitter Action
*TXIE - Transmit Interrupt Enable
*DF - Diagnostic Fail
*TDE - Transmit DMA Error
*Tx Line - Line which set TXA
*RDA - Received Data Available
*RXIE - Receiver Interrupt Enable
*MR - Master Reset
*SKIP - Skip Self-Test
*Line - Select LPR through TBCT

=== Line Parameter Register (LPR)===
{{16bit-header}}
| colspan=4 | TSpeed || colspan=4 | RSpeed || STOP || EVEN || PARE || colspan=2 | CLEN || colspan=2 | DICD || Unused
{{16bitoctal-bitout}}

===Line Status Register (STAT)===
{{16bit-header}}
| DSR || Unused || RI || DCD || CTS || colspan=2 | Unused || DHU || colspan=8 | Not Present
{{16bitoctal-bitout}}

=== Line Control Register (CTRL)===
{{16bit-header}}
| colspan=3 | Unused || RTS || colspan=2 | Unused || DTR || LTYP || colspan=2 | MAINT || FXOFF || OAUTO || BREAK || RXE || IAF || TXA
{{16bitoctal-bitout}}

==Further reading==

* ''DHU11 Technical Manual '', EK-DHU11-TM-001 (not yet online - it's bound, so a copy may have to be sacrificed to scan it)
* ''DHUll Field Maintenance Print Set'', MP-01794-01 (not yet online)

==External links==

* [http://www.bitsavers.org/pdf/dec/unibus/DHU11/EK-DHU11-UG-002_DHU11_Interface_Users_Guide_Nov86.pdf DHU11 User Guide] (EK-DHU11-UG-002)

[[Category: UNIBUS Asynchronous Serial Interfaces]]

DZ11 asynchronous serial line interface

2026-10-05T19:21:25Z

Jnc: /* External links */ Bitsavers has reorganized a bit

[[Image:M7819.jpg|thumb|right|250px|M7819 EIA DZ11 card]]

The '''DZ11''' was a [[UNIBUS]] 8 port [[asynchronous serial line]] mux card for [[Digital Equipment Corporation|DEC]] computers. It used [[programmed I/O]], and thus could present a considerable load on the [[Central Processing Unit|CPU]] when running a high speed line, using [[interrupt]]s. A 64-entry [[First-In First-Out buffer|FIFO buffer]] silo was provided on the input side.

Both [[EIA RS-232 serial line interface|EIA]] and [[20mA current loop serial line interface|20mA]] physical layers were supported; the EIA model could operate with [[full-duplex]] [[modem]]s. It provided program-set [[baud rate]]s (up to 9600 baud), but not split speed. [[Break]] could be detected or generated on each line.

A single EIA DZ11 with an EIA-specific 16-line [[distribution panel]] was denominated as a DZ11-A; an EIA board by itself was a DZ11-B, and a distribution panel with two boards is a DZ11-E. Similarly, a single 20mA DZ11 with a 20mA-specific 16-line [[distribution panel]] was denominated as a DZ11-C, the 20mA board by itself was a DZ11-D, and a distribution panel with two boards is a DZ11-F.

==Implementation==

Physically, it was a [[DEC card form factor|hex]] card, which plugged into an [[Small Peripheral Controller|SPC]] [[backplane]] slot. The EIA version was the M7819, and the 20mA one was the M7814.

On the M7819, a [[flat cable]] led from a [[Berg connector]] on the card via a [[static filter]] to an H317-E EIA distribution panel (for ID purposes, the [[DEC part number]] for the [[printed circuit board|PCB]] of the H317-E is 54-11928). The H317-E held 16 [[EIA RS-232 serial line interface#Connectors|DB25 male connectors]] (DB-25P) wired as DTEs, enough for two DZ11 cards.

Accessories for the M7819 EIA version are:

* BC05W-15 50 conductor signal cable
* H7004C Static Filter
* BC06L-0J 50 conductor signal cable
* H317-E EIA distribution panel
* Cable Box assembly
* H325 test connector (single line)
* H3271 staggered test connector

[[Image:H3006Panel.jpg|thumb|right|200px|H3006]]

The later H3006 distribution panel for the EIA version was part of DEC's modular back-panel system.

For the 20mA M7814, substitute the:

* BC08S-15 40 conductor signal cable
* H7004B Static Filter
* BC06K-0J 40 conductor signal cable
* H317-F 20mA distribution panel
* H3190 staggered test connector.

==Device registers==

{| border=1
! Register !! Abbreviation !! Address
|-
|Control and Status Register || CSR || 760100
|-
|Receiver Buffer Register* || RBUF || 760102
|-
|Line Parameter Register* || LPR || 760102
|-
|Transmit Control Register || TCR || 760104
|-
|Modem Status Register || MSR || 760106
|-
|Transmit Data Register || TDR || 760106
|}

The RBUF and LPR share an address, as do the MSR and TDR: the RBUF is read only, and the LPR is write only; the MSR is read only, and the TDR is write only. Registers marked with a '*' are [[word]]-width only, no byte operations.

The [[address]]es shown are for the first DZ11 in a system (provided that there are no other devices in the [[floating device address space]]); additional ones are normally set to be at 760110, 760120, etc.

===Control and Status Register (CSR)===
{{16bit-header}}
| TRDY || TIE || SA || SAE || Unused || colspan=3 | Tx Line || RDONE || RIE || MSE || CLR || MAINT || colspan=3 | Unused
{{16bitoctal-bitout}}

*TRDY - Transmitter Ready
*TIE - Transmitter Interrupt Enable
*SA - Silo Alarm
*SAE - Silo Alarm Enable
*Tx Line - Line ready to transmit
*RDONE - Received Done
*RIE - Receiver Interrupt Enable
*MSE - Master Scan Enable
*CLR - Clear input FIFO, CSR and [[UART]]s
*MAINT - Maintenance loopback enabled

=== Receiver Buffer Register (RBUF)===
{{16bit-header}}
| DV || OVR || FRERR || PERR || Unused || colspan=3 | Rx Line || colspan=8 | RBUF
{{16bitoctal-bitout}}

=== Line Parameter Register (LPR)===
{{16bit-header}}
| colspan=3 | Unused || RXON || colspan=4 | Speed || ODDP || PAREN || STOP || colspan=2 | CLEN || colspan=3 | Line
{{16bitoctal-bitout}}

===Transmit Control Register (TCR)===
{{16bit-header}}
| colspan=8 | DTR ||colspan=8 | Line Enabled
{{16bitoctal-bitout}}

=== Modem Status Register (MSR)===
{{16bit-header}}
| colspan=8 | CD ||colspan=8 | RI
{{16bitoctal-bitout}}

=== Transmit Data Register (TDR)===
{{16bit-header}}
| colspan=8 | Break ||colspan=8 | TBUF
{{16bitoctal-bitout}}

==Further reading==

* ''DZ11-C, D, F (20mA) Field Maintenance Print Set'', (MP00253)

==External links==

* [http://www.bitsavers.org/pdf/dec/unibus/DZ11/EK-DZ110-UG-002_DZ11_Users_Guide_Feb79.pdf DZ11 user's guide] (EK-DZ110-UG-002)
* [http://www.bitsavers.org/pdf/dec/unibus/DZ11/EK-DZ110-TM-002_DZ11_Asynchronous_Multiplexer_Technical_Manual_Oct78.pdf DZ11 asynchronous multiplexer technical manual] (EK-DZ110-TM-002)
* [http://www.bitsavers.org/pdf/dec/unibus/DZ11/MP00132_DZ11_RevB_Engineering_Drawings_May78.pdf DZ11-A,B,E (EIA) Field Maintenance Print Set] (MP00132)

[[Category: UNIBUS Asynchronous Serial Interfaces]]

KLESI Low-End Storage Interconnect

2026-10-05T17:05:49Z

Jnc: /* External links */ Bitsavers has reorganized a bit

The '''KLESI Low-End Storage Interconnect''' controllers are a series of [[device controller]]s which use [[Mass Storage Control Protocol|MSCP]] and TMSCP [[protocol]]s, running over a [[Low End System Interconnect]] physical interconnect, to interface with [[disk]]s and [[magnetic tape drive]]s.

They include the '''KLESI-UA''' ('''M8739''') for the [[UNIBUS]], the '''KLESI-QA''' ('''M7740''') for the [[QBUS]] and the '''KLESI-B''' ('''T1014''') for the [[VAXBI]] bus. The -UA is a [[DEC card form factor|quad]] card which plugs into an [[Small Peripheral Controller|SPC]] slot. The -QA is a dual (although the -S variant is packaged in a quad form, with an [[S-box]] handle, for the [[BA200 series enclosure]]s). The KLESI-B is contained on a standard BI module.

One main use was with the TU81E/TU81-Plus variant of the [[TU81 Streaming Tape Unit‎]]; it was also used with the [[RC25 disk drive]].


{{semi-stub}}

==Further reading==

* ''KLESI-B Module User and Installation Guide'' (EK-LESIB-UG)
* ''KLESI-B Adapter Technical Manual'' (EK-LESIB-TM)

==External links==

* [http://www.vaxhaven.com/images/0/08/EK-KLESI-IN-001.pdf KLESI-SF Q22-bus Adapter Option Installation Guide] (EK-KLESI-IN-001)
* [http://www.bitsavers.org/pdf/dec/qbus/KLESI/MP01876_KLESI_EngrDrws_Aug84.pdf KLESI Field Maintenance Print Set] (MP-01876-0-0 - covers the KLESI-UA and KLESI-QA)

[[Category: UNIBUS Storage Controllers]]
[[Category: QBUS Storage Controllers]]
[[Category: VAXBI Storage Controllers]]
[[Category: LESI]]

DB11-A Bus Repeater

2026-10-05T16:55:00Z

Jnc: /* External links */ Bitsavers has reorganized a bit

The '''DB11-A Bus Repeater''' allows a [[UNIBUS]] to double the number of [[peripheral]]s connected to the [[bus]] (in terms of the combined [[analog]] load).

It [[terminator|terminates]] (in analog terms) the first section of the bus, and active [[digital]] [[logic]] repeats all the [[signal]]s though onto the second section (or from the second back to the first, when required); the two sections are thus logically connected, but not in purely analog terms.

It consists of a custom [[system unit]] [[backplane]], holding a number of smaller [[FLIP CHIP]]s; mostly [[DEC card form factor|singles]] (see table below), with one dual (M7213).

{| class="wikitable"
! Type !! Count || Function
|-
| M783 || 1 || Bus driver
|-
| M784 || 1 || Bus receiver
|-
| M785 || 4 || Bus transceiver
|-
| M7212 || 3 || Address buffer
|-
| M7213 || 1 || Buffer master
|-
| M7248 || 1 || BBSY repeater
|-
| M930 || 2 || UNIBUS terminator
|}

Board locations (as seen from the board insertion side of the backplane, not the [[wire-wrap]] pin side, as is common in [[Digital Equipment Corporation|DEC]] documentation) are:

{| class="wikitable"
! !! colspan="6" | Connector
|-
! Slot !! A !! B !! C !! D !! E !! F
|-
| 1 || colspan="2" style="text-align:center;" | UNIBUS A In || M7248 || M7212 || M7212 || M7212
|-
| 2 || colspan="2" style="text-align:center;" | UNIBUS A termination || colspan="2" style="text-align:center;" | Unused || M784 || M783
|-
| 3 || Power || Unused || colspan="2" style="text-align:center;" | M7213 || M785 || M785
|-
| 4 || colspan="2" style="text-align:center;" | UNIBUS B Out || colspan="2" | UNIBUS B termination || M785 || M785
|}

For installation in later [[BA11 mounting boxes]], the paddle card of a G772 [[system unit]] [[harness]] adaptor can be plugged into the [[DEC edge connector contact identification|3A slot]]; the [[DEC power distribution connectors]] on the other end of the adaptor plug into those of the BA11.

==External links==

* [http://www.bitsavers.org/pdf/dec/unibus/DB11-A/EK-DB11A-TM-002_DB-11A_Bus_Repeater_Manual_Aug74.pdf DB11-A bus repeater manual] - (EK-DB11A-TM-002)
* [http://www.bitsavers.org/pdf/dec/unibus/DB11-A/DB11-A_RevS_Engineering_Drawings_Jan76.pdf DB11-A Engineering Drawings] - Various bus drivers, repeaters and terminators

[[Category: UNIBUS]]

MS11 32KB MOS memory

2026-10-05T16:14:43Z

Jnc: /* External links */ Bitsavers has reorganized a bit

The '''MS11-E''', '''MS11-F''', '''MS11-H''' and '''MS11-J''' are the different configurations of [[Digital Equipment Corporation|DEC]]'s first commodity [[Metal Oxide Semiconductor|MOS]] [[UNIBUS]] [[main memory]] card, the '''M7847'''. They plug into a [[Modified UNIBUS Device|MUD]] [[backplane]] (''only''; not [[Small Peripheral Controller|SPC]]).

Fully populated with 4Kx1 [[Dynamic RAM|DRAM]] [[integrated circuit|chips]], it is known as the MS11-J, and holds 32K [[byte]]s. The quarter-, half- and three-quarter-populated versions are the MS11-E, -F and -H, respectively; with 8KB, 16KB and 24KB. (The '-G' is almost certainly not part of the sequence since 'G' is not in the [[DEC alphabet]].)

There are [[parity]] versions of each; the '''MS11-EP''', '''-FP''', '''-HP''' and '''-JP'''; to have the parity operate, these require an [[M7850 parity controller]] in the same backplane as the memory card. The M7847 is a [[DEC card form factor|hex]] card, so it cannot go in the end slots of the backplane.

The [[access time]] is 550 nsec (1250 nsec maximum on [[memory refresh]] conflict), and the [[cycle time]] is 700 nsec (1400 nsec maximum on refresh conflict). Refresh cycle time is 25 μsec (typical), 22.5 μsec (minimum).

The board has provision to use battery backup power to retain data during a power outage. Configuration is by [[Dual Inline Package|DIP]] switches; the first DEC memory to do so.

==External links==

* [http://www.bitsavers.org/pdf/dec/pdp11/memory/MS11-E/EK-MS11E-OP-001_Oct76.pdf MS11-E–J MOS memory user's manual] (EK-MS11E-OP-001)
* [http://www.bitsavers.org/www.computer.museum.uq.edu.au/pdf/EK-MS11E-MM-001%20MS11-E-J%20MOS%20Memory%20Maintenance%20Manual.pdf MS11-E–J MOS memory maintenance manual] (EK-MS11E-MM-001)
* [http://www.bitsavers.org/pdf/dec/pdp11/memory/MS11-E/MP00021_MS11-E_Oct1975.pdf MS11-E Engineering Drawings] (MP00021)

[[Category: UNIBUS Memories]]

RL11 disk controller

2026-10-05T16:06:00Z

Jnc: /* External links */ Bitsavers has reorganized a bit

[[Image:RL11 M7762.jpg|250px|right|thumb|RL11 M7762 card]]

The '''RL11''' disk controllers (the original RL11 for the [[UNIBUS]], and the '''RLV11''' and '''RLV12''' for the [[QBUS]]) were for the [[RL01/02 disk drive|RL01 and RL02]] [[disk|disk drive]]s. (These drives protect the data, and [[sector]] headers, with separate [[cyclic redundancy check|CRCs]].)

The RL11 was a [[DEC card form factor|hex]] board, the M7762. The RLV11 consisted of two quad boards, the M8013 and M8014, which used the [[CD interconnect]] to communicate; it was [[program compatible]] with the RL11. The RLV12 was a single quad board, the M8061; it was mostly program compatible, but added a 'Bus Address Extension' [[register]] for use on [[QBUS#Variable address size|Q22]] systems.

All have a 40-pin [[Berg connector]] header holding a [[flat cable]], which runs to a bulkhead-mounted converter from the flat cable to a special inter-drive cable (round in cross-section, with special locking connectors). (If the flat cable is plugged in the wrong way around, nothing is damaged; the drive merely turns on its 'fault' light.)

The cable runs from the converter to the first drive; up to 4 drives can be connected to a single controller, using a bus running from one drive to the next, with a [[terminator]] in the last drive of the string.

==Controller capabilities==

[[Image:rlv12.jpg|200px|right|thumb|RLV12 card]]

The controller and drive combination can execute 8 different commands:

* No Operation
* Write Check
* Get Status
* Seek
* Read Header
* Write Data
* Read Data
* Read Data Without Header Check

Implied [[seek]]s (i.e. setting the disk address, and then starting a read or write operation, which is intended to happen at that address) are not supported; an explicit seek to the desired [[cylinder]] must be performed before the read or write. (This is in part because the Disk Address register is shared between the cylinder move number, during a seek operation, and the starting sector number, during a read or write operation.) Spiral reads and writes (i.e. multi-block reads which start on one [[track]], and overflow to the next) are also not supported; multiple separate read/write commands are needed, with a seek to the next track between each pair.

==Device registers==

The RL11 controller includes 4 (5 for the RLV12) read-write [[register]]s:

{| border=1
! Register !! Abbreviation !! Address
|-
|Control Status Register || RLCS || 774400
|-
|Bus Address Register || RLBA || 774402
|-
|Disk Address Register || RLDA || 774404
|-
|Multipurpose Register || RLMP || 774406
|-
|Bus Address Extension Register<br>''RLV12 only'' || RLBAE || 774410
|}

===774400: Control Status Register (RLCS)===
{{16bit-header}}
| CERR || DE || NXM || DLT/HNF || DCRC/ HCRC || OPI || colspan=2 | DRVSEL || CRDY || IE || colspan=2 | BUS ADDR EX || colspan=3 | FUNC || DRDY
{{16bit-bitout}}

{| class="wikitable"
! Function Code !! Function
|-
| 0 || No Operation
|-
| 1 || Write Check
|-
| 2 || Get Status
|-
| 3 || Seek
|-
| 4 || Read Header
|-
| 5 || Write Data
|-
| 6 || Read Data
|-
| 7 || Read Data, No Header Check
|}

OPI - Operation Incomplete
DCRC/HCRC/WCE - Data CRC/Header CRC/Write Check Error
DLT/HNF - Data Late / Header Not Found
DE - Drive Error ('Get Status' will provide details)
CERR - Composite Error

===774402: Bus Address Register (RLBA)===
{{16bit-header}}
| colspan=15 | BA15 <---> BA01 || 0
{{16bit-bitout}}

===774404: Disk Address Register (RLDA)===

During a 'Seek' command on an RL01:
{{16bit-header}}
| 0 || colspan=8 | CYL ADDR DIFF || colspan=2 | Reserved || HD SEL || 0 || DIR || 0 || 1
{{16bit-bitout}}

During a 'Seek' command on an RL02:
{{16bit-header}}
| colspan=9 | CYL ADDR DIFF || colspan=2 | Reserved || HD SEL || 0 || DIR || 0 || 1
{{16bit-bitout}}

During a 'Read Data' or 'Write Data' command on an RL01:
{{16bit-header}}
| 0 || colspan=8 | CYL ADDR || HD SEL || colspan=6 | SECTOR
{{16bit-bitout}}

During a 'Read Data' or 'Write Data' command on an RL02:
{{16bit-header}}
| colspan=9 | CYL ADDR || HD SEL || colspan=6 | SECTOR
{{16bit-bitout}}

During a 'Get Status' command:
{{16bit-header}}
| colspan=8 | Unused || colspan=4 | MBZ || RESET || 0 || GT STA || 1
{{16bit-bitout}}

===774406: Multipurpose Register (RLMP)===

During a 'Read Data' or 'Write Data' command:
{{16bit-header}}
| colspan=3 | 111 || colspan=13 | WORD COUNT
{{16bit-bitout}}

During a 'Get Status' command:
{{16bit-header}}
| WDE || CHE || WL || SKTO || SPE || WGE || VC || DSE || Rsvd || HS || CO || HO || BH || colspan=3 | STATE
{{16bit-bitout}}

{| class="wikitable"
! State Code !! State
|-
| 0 || Load Cartridge
|-
| 1 || Spin Up
|-
| 2 || Brush Cycle
|-
| 3 || Load Heads
|-
| 4 || Seek
|-
| 5 || Lock On
|-
| 6 || Unload Heads
|-
| 7 || Spin Down
|}

During a 'Read Header' command, three successive reads to the Multipurpose Register will return in the first word, on an RL01:
{{16bit-header}}
| 0 || colspan=8 | CYL ADDR || HD SEL || colspan=6 | SECTOR
{{16bit-bitout}}

and on an RL02:
{{16bit-header}}
| colspan=9 | CYL ADDR || HD SEL || colspan=6 | SECTOR
{{16bit-bitout}}

followed by all 0's in the second word, and the header CRC in the third.

===774410: Bus Address Extension Register (RLBAE)===
{{16bit-header}}
| colspan=10 | Unused || colspan=6 | BA21 <---> BA16
{{16bit-bitout}}

'''Note:''' This register is present in the RLV12 ''only''.

==Bootstraps==

This [[bootstrap]] (which is position-independent [[object code]], so it can be placed anywhere; 04000 is good) will load the block at sector 0 of cylinder 0 of drive 0 into [[main memory]] at [[address]] 0:

{| border=1
! Address !! Data !! Mnemonic !! Description
|- style="background-color: #ccccdd;"
|1000||012700||MOV #174400,R0 ||Move the address of the Control Status register into R0
|- style="background-color: #ccccff;"
|1002||174400|| || (constant)
|- style="background-color: #ccccdd;"
|1004||012760||MOV #177400,6(R0) ||Move block size (negative) into Multipurpose register
|- style="background-color: #ccccff;"
|1006||177400|| || (constant)
|- style="background-color: #ccccff;"
|1010||000006|| || (constant)
|- style="background-color: #ccccdd;"
|1012||012710||MOV #14,@R0 ||Move 'Read Go' command into CSR
|- style="background-color: #ccccff;"
|1014||000014|| || (constant)
|- style="background-color: #ccccdd;"
|1016||105710||TSTB (R0) ||Test for 'Done' bit in CSR
|- style="background-color: #ccccff;"
|1020||100376||BPL 1016 ||Jump backward if not set
|- style="background-color: #ccccdd;"
|1022||005007||CLR PC ||Start loaded bootstrap with jump to 0
|}

Note that the INIT pulse caused by hitting the [[front panel]]'s 'Start' button will clear the Bus Address register, so that the loaded block will be placed at location 0; and the Disk Address register, so that sector 0 will be read. If the drive's heads are not on cylinder 0, since a seek on an RL01/02 is ''relative'', a 'Read Header' command would have to be done before a seek could be commanded (or the [[device driver]] must remember the current cylinder), and that all would require a fair amount of code. To ensure that the drive is on cylinder 0 for the bootstrap, the drive should be power cycled before starting the bootstrap.

==Further reading==

* [https://www.bitsavers.org/pdf/dec/qbus/micronoteReprints.pdf RL01 Type-in Bootstrap], [[MicroNote]] #063 (pg. 207 of the PDF)

==External links==

* [http://www.bitsavers.org/pdf/dec/unibus/RL11/EK-ORL11-TD-001_RL11tech.pdf RL11 Controller Technical Description Manual] (EK-0RL11-TD-001)
* [http://www.bitsavers.org/pdf/dec/qbus/RLV11/EK-RLV11-TD-001_RLV11_Controller_Technical_Description_Manual_Mar78.pdf RLV11 Controller Technical Description Manual] (EK-RLV11-TD-001)
* [http://www.bitsavers.org/pdf/dec/qbus/RLV12/EK-RLV12-UG-002_Mar82.pdf RLV12 Disk Controller User's Guide] (EK-RLV12-UG-002)
* [http://www.bitsavers.org/pdf/dec/qbus/RLV12/EK-RLV12-TD-001_RLV12_Technical_Description_Oct81.pdf RLV12 Technical Description] (EK-RLV12-TD-OOl)
* [http://www.bitsavers.org/pdf/dec/unibus/RL11/MP00153_RL11EngrDrws.pdf RL11 Field Maintenance Print Set] (MP00153)
* [http://www.bitsavers.org/pdf/dec/unibus/RL11/RL11_schematics.pdf RL11-AK Field Maintenance Print Set] (MP00526)
* [http://www.bitsavers.org/pdf/dec/qbus/RLV11/MP00635_RLV11_May78.pdf RLV11 Field Maintenance Print Set] (MP00635)
* [http://www.bitsavers.org/pdf/dec/qbus/RLV12/MP01282_RLV12_EngrDrws.pdf Field Maintenance Print Set (RLV12)] (MP01282)

[[Category: UNIBUS Storage Controllers]]
[[Category: QBUS Storage Controllers|RLV11]]

RK11-C disk controller

2026-10-05T15:11:47Z

Jnc: /* External links */ +RK11-C Indicator Connections

[[Image:DBRK11C.jpg|350px|thumb|right|RK11-C disk controller, Double Buffered version]]

The '''RK11-C''' is the earliest known version of the [[RK11 disk controller]]. (Nothing is known of the -A and -B, if they ever existed as products, although see [[RK11 disk controller#Early RK11 version|here]] for more about the RK11-C's predecessor). It is mostly [[program compatible]] with the replacement [[RK11 disk controller#RK11-D|RK11-D]].

Although the drive interface is slightly different between the RK11-C and RK11-D, the RK11-C can handle both the earlier [[RK02/03 disk drive]]s, and the later [[RK05 disk drive|RK05s]] (the latter primarily intended for use with the RK11-D - see below).

Like many of the earlier large [[device controller]]s for the [[PDP-11]], it was a large custom [[wire-wrap]]ped [[backplane]] which bolted into the front or back of a 19 inch rack, such as an [[H960 rack|H950]]; into it plugged about 40 small M-Series [[FLIP CHIP]]s.

The backplane is wired for connection to a standard [[DEC indicator panel]], but no inlay for such has even been sighted, although the RK11-C Engineering Drawings allow one to work out exactly what such an inlay would have looked like. It does however appear than the hypothesized earlier version (above) did have such an indicator panel.

==Drive buses and RK05 compatibility==

The RK11-C has two different drive buses, each which can handle up to four drives. (The buses are not independent - most lines are shared between the two; so only one can be active at a time.) The only lines not in common are the 'drive select' lines (A-D on bus 1 - slot 12 on the backplane, and E-F, H, J on bus 2 - slot 10). Each select line is assigned to one drive; to select that drive, the corresponding line is asserted.

RK11-D's use a different, but upwardly compatible drive select mechanism, and RK05's can detect whether they are connected to an RK11-C or RK11-D, and respond appropriately.

==Double Buffered RK11-C==

[[Image:RK11-C-DB_DataPaths.jpg|295px|right|thumb|RK11-C-DB data paths (from the last page of the engineering drawings)]]

There is also a rare variant of the RK11-C, the 'Double Buffer' RK11-C. It adds two 16-bit buffer registers (ABUF and BBUF), which are chained in an alternate data path to the RKDB buffer register from the two sources that can feed it (the UNIBUS and the DSB - Data Serial Buffer, where data to/from the disk is serialized).

The motivation is not explicitly known (no documentation other than the engineering drawings is now extant), but it likely prevented under-run/over-run errors when there was considerable competing UNIBUS [[Direct Memory Access|DMA]] traffic.

===Engineering drawings===

The engineering drawings for the Double Buffer RK11-C are very similar to those of the standard RK11-C. The differences are listed below.

(The engineering drawings available online for the original RK11-C have slightly different numbering for some pages, due to a change involving page 18, 'Disk Cable and Termination'. The Double Buffer set includes that page, but numbered it 21. The re-numbering of that first drawing from 18 to 21 caused the prints numbered from 19 to 21 in the original RK11-C set to be numbered one lower in the Double Buffer set; e.g. 'RKDB Data Paths' was 21 in the original RK11-C set, and is 20 in the Double Buffer set, and 'Bus "D" Drvrs and Rcvrs' changed from 19 to 18.)

'''New prints:'''

* 24 - DSB/Bus -> ABuf Controls
* 25 - ABuf/BBuf Reg
* 26 - Interbuffer Transfer Control
* 27 - Buffer Control

'''Major changes:'''

* 10 - RKDB and Control
* 11B - Reg Sel, NPR & Int Control

'''Minor changes:'''

* 13 - Adder Control (Adder Control #2 flop set input logic)
* 15 - RKBA - RKWC - RKMR (logic lower left corner)
* 16 - Errors (logic center driving DLT flop)
* 17 - Cable Drivers (hand-written gate lower left)
* 20 - RKDB Data Paths (replace 'BUS D' with 'BBUF' on all data bits)

== Module count table==

The following table gives a listing of the FLIP CHIPs used in the RK11-C and the Double-Buffered RK11-C. (Drawn from module utilization drawings, confirmed in module count charts.)

Single height boards:

{| class="wikitable"
! Type !! RK11-C !! Double-Buffered !! Function
|-
| G736 || 1 || 1 || Jumper
|-
| G740 || 1 || 1 || Disk selection
|-
| colspan="3" |
|-
| M002 || 1 || 3 || 15 Loads
|-
| M105 || 1 || 1 || [[M105 Address Selector|Address selector]]
|-
| M111 || 2 || 5 || Inverter
|-
| M112 || 5 || 7 || NOR gate
|-
| M113 || 7 || 10 || 10 x 2-Input NAND gates
|-
| M115 || 3 || 4 || 8 x 3-Input NAND gates
|-
| M116 || 3 || 3 || 6 x 4-Input NOR gates
|-
| M117 || 3 || 4 || 6 x 4-Input NAND gates
|-
| M119 || 2 || 2 || 3 x 8-Input NAND gates
|-
| M121 || 3 || 3 || AND/NOR gates
|-
| M141 || 2 || 2 || NAND/NOR gates
|-
| M149 || 10 || 12 || 9 x 2-NAND wired OR matrix
|-
| M161 || 1 || 1 || Binary to octal/decimal decoder
|-
| M163 || 1 || 1 || Dual binary to decimal decoder
|-
| M203 || 4 || 4 || 8 x SR flip-flops
|-
| M205 || 3 || 4 || 5 x 'D' flip-flops
|-
| M207 || 1 || 1 || J-K Flip-flops (3-3 configuration)
|-
| M208 || 2 || 6 || 8-bit buffer shift register
|-
| M214 || 3 || 3 || 6-bit register
|-
| M216 || 5 || 5 || 6 x flip-flops
|-
| M236 || 1 || 1 || 12-bit binary up/down counter
|-
| M238 || 1 || 1 || Synchronous 4-bit up/down counter
|-
| M239 || 2 || 2 || 3 x 4-bit up/down counter/register
|-
| M304 || 3 || 5 || One shot delay
|-
| M307 || 3 || 3 || Integrating one shot
|-
| M405 || 1 || 1 || Crystal clock
|-
| M606 || 0 || 2 || Pulse generator
|-
| M611 || 1 || 1 || High speed power inverter
|-
| M617 || 1 || 1 || 6 x 4-input NAND buffers
|-
| M623 || 3 || 3 || Bus driver
|-
| M782 || 1 || 1 || [[M782 Interrupt Control|Interrupt control]]
|-
| M784 || 3 || 3 || UNIBUS receivers
|-
| M796 || 1 || 1 || UNIBUS master control
|-
| M797 || 1 || 1 || Register select
|-
| M798 || 1 || 1 || UNIBUS drivers
|}

Double height boards:

* M795 - Word Count and Current Memory Address

==Module Utilization chart==

The following table gives the FLIP CHIP locations in the backplane for the RK11-C and the Double-Buffered RK11-C (added FLIP CHIPs for the latter are in ''italics''). The Flip Chip module utilization chart is as follows (* = Connector):

{| class="wikitable"
! Slot !! A !! B !! C !! D
|-
| 1 || colspan="2" style="text-align:center;" | UNIBUS in || ''M606'' || ''M113''
|-
| 2 || colspan="2" style="text-align:center;" | UNIBUS out || ''M115'' || ''M002''
|-
| 3 || ''M149'' || ''M149'' || ''M208'' || ''M208''
|-
| 4 || ''M111'' || ''M002'' || ''M205'' || ''M113''
|-
| 5 || M105 || M784 || ''M208'' || ''M208''
|-
| 6 || M782 || M796 || ''M304'' || ''M304''
|-
| 7 || colspan="2" style="text-align:center;" | M795 || ''M606'' || ''M112''
|-
| 8 || M784 || M784 || ''M112'' || ''M111''
|-
| 9 || ''M117'' || ''M111'' || M623 || M307
|-
| 10 || colspan="2" style="text-align:center;" | Disk bus 2* || M623 || M307
|-
| 11 || || ''M113'' || M623 || M307
|-
| 12 || colspan="2" style="text-align:center;" | Disk bus 1* || M207 || M163
|-
| 13 || M798 || G736 || G740 || M405
|-
| 14 || M149 || M149 || M116 || M161
|-
| 15 || M149 || M149 || M304 || M119
|-
| 16 || M149 || M149 || M113 || M113
|-
| 17 || M239 || M238 || M216 || M141
|-
| 18 || M239 || M214 || M115 || M115
|-
| 19 || M214 || M214 || M121 || M112
|-
| 20 || M208 || M208 || M111 || M111
|-
| 21 || M203 || M203 || M112 || M112
|-
| 22 || M149 || M149 || M205 || M117
|-
| 23 || M149 || M149 || M203 || M203
|-
| 24 || M121 || M002 || M116 || M115
|-
| 25 || M216 || M797 || M611 || M617
|-
| 26 || M141 || M119 || M113 || M304
|-
| 27 || M304 || M112 || M112 || M113
|-
| 28 || M236 || M121 || M216 || M216
|-
| 29 || M205 || || M117 || M117
|-
| 30 || colspan="2" style="text-align:center;" | W130* || M113 || M113
|-
| 31 || colspan="2" style="text-align:center;" | 6775* || M113 || M205
|-
| 32 || colspan="2" style="text-align:center;" | 6775* || M116 || M216
|}

W130 = Maintenance board (optional)
<br>
6775 = Cable to indicator panel

In the ordinary RK11-C, slots C08 and D08 hold pass-through connectors, which allow [[KM11-A Maintenance Set]]s to be plugged in and used from the outside of the rack holding the RK11-C. A pair of [[Flexprint cable]]s connect them to the 'usual' KM11 locations, in slots A30 and B30.

==External links==

* [http://www.bitsavers.org/pdf/dec/unibus/RK11-C/RK11-C_manual1971.pdf RK11-C moving head disk drive controller manual] (DEC-11-HRKA-D)
* [http://www.bitsavers.org/pdf/dec/unibus/RK11-C/RK11-C_schemFeb1971.pdf RK11-C moving head disk drive controller engineering drawings]
* [http://ana-3.lcs.mit.edu/~jnc/tech/pdp11/dload/RK11-C-DB_EngrDrws_Dec72.pdf RK11-C-DB Double Buffer Disk Control Engineering Drawings]
* [https://www.bitsavers.org/pdf/dec/unibus/5408458_ind_panel/rk11c_conn.tif RK11-C Indicator Connections]
* [https://fritzm.github.io/unix-v6-trouble-1.html PDP-11/45: V6 Unix Troubleshooting, Part I] [https://fritzm.github.io/unix-v6-trouble-2.html Part II] - a wonderful, lengthy and painful example of [[Vonada's Engineering Maxims|Vonada's Maxim #12]] at work on an RK11-C

[[Category: UNIBUS Storage Controllers]]

RK11 disk controller

2026-10-05T15:07:46Z

Jnc: /* External links */ Bitsavers has reorganized a bit

The '''RK11''' and '''RKV11''' series of controllers for the [[UNIBUS]] and [[QBUS]] are for the earlier RK moving-[[head]] [[magnetic storage|magnetic]] [[disk]] [[drive]]s ([[RK02/03 disk drive|RK02]]-[[RK05 disk drive|RK05]]), all based on the [[IBM 2315]] drive and pack.

(The later [[RK06/07 disk drive|RK06 and RK07]], and their controller, the [[RK611]], are a different and entirely incompatible drive and pack.)

There are several models of the RK11, which are basically identical in their programming interface; differences between them are discussed in the sections on the individual models (below).

The UNIBUS RK11's all connect to the RK drive(s) through a [[bus]] carried over a [[BC11A]] cable, the standard UNIBUS cable.

==Early RK11 version==

Although the [[RK11-C disk controller|RK11-C]] (below) is the earliest documented version, there are a few clues which indicate that there was an earlier version (one for which no documentation remains).

First, there is an image of a [[DEC indicator panel]] (image [http://ana-3.lcs.mit.edu/~jnc/tech/pdp11/jpg/panels/RK11B.jpg here]) which seems to be from a pre-RK11-C; it clearly seems to be an RK11 panel of some sort, but the pinout of the RK11-C indicator panel connector (engineering drawing "RK11-C Indicator Connectors: RK11-C-23") has differences with this one.

In particular, on the panel in the image, the lower right line of lights on the panel shows 3 bits of Major State; on the RK11-C prints (on connector B32) there are 5 individual bits (Postamble, Checksum, Data, Header, Preamble). To explore this further, on the "Major States" RK11-C drawing (RK11-C-04), in the upper left corner, there is a row of 6 flops, each labeled with one of those states (plus one for 'Idle'), arranged in a chain - the output of each driving an individual light. However, the 3 bits for 'Major State' on the display panel imply it is binary coded - likely implemented with a counter.

Also, the signal "COUNT MSR" (likely 'Major State Register') is exactly what one would expect to see if the major state had previously been held in a counter, not a string of flops. It makes no sense to expend the effort synthesize that signal (on the next page, RK11-C-05, "MSR Control") when the individual signals which go into it could have been used, as is, to clock each flop in the chain.

A reasonable ''guess'', in light of these facts, is that in some previous version, a counter had been used, but had had a problem of some sort, and had therefore been replaced by the string of flops. (The reason is unknown, but perhaps it was a binary counter, not [[Gray code]], and the decoding into states was producing glitches.)

A plausible scenario is that such an earlier version was produced in very small numbers - perhaps as prototypes, only internal to DEC. (If there had been problems discovered with glitches in the major state counter, they would not have wanted to release it as a product.) Or if it was released as a product, perhaps they were all recalled and replaced with RK11-C's.

In this regard, it is interesting to note the DEC ''Spare Module Handbook'', lists only the RK11-C and -D, but '''does''' list the [[KT11-B]], a ''rara avis'' indeed. This argues that the predecessor did not exist 'in the wild'.

==RK11-C==

{{Main article | RK11-C disk controller}}

Like many of the earlier large peripheral controllers for the [[PDP-11]], the RK11-C was a large custom [[wire-wrap]]ped [[backplane]] which bolts into the front or back of a 19 inch rack, such as an [[H960 rack|H960]]; into it were plugged about 40 small M-Series [[FLIP CHIP]]s.

The RK11-C supports up to 4 drives per device bus (it uses 4 different 'select' lines on the bus, one of which is asserted at a time), and has two device busses.

==RK11-D==

The RK11-D was a re-implementation of the RK11-C on four [[DEC card form factor|quad]] cards (M7254-7), which plugged into a custom-wired 4 slot hex-high [[system unit]] [[backplane]], for a [[BA11 mounting boxes|BA11]] slide-out mounting box.

It was [[program compatible]] with the RK11-C, except that the RK11-D did not contain the Maintenance Register of the earlier controller. In the RK11-D, the bus location of the MR responds, but according to the engineering drawings, it reads as zero, and written data is ignored.

The RK11-D supports up to 8 drives per device bus (it uses 3 'select' lines on the bus, with the drive number encoded in binary), and has only one device bus.

The RK11-D also has a 6-word [[First-In First-Out buffer|FIFO buffer]] between the disk and the bus (see sheet 7 of the M7256 engineering drawings). The original RK11-C had only one word of buffering, which was probably not enough, and likely the reason for the [[RK11-C disk controller#Double Buffered RK11-C|double-buffered RK11-C version]].

==RK11-E==

The RK11-E (sometimes called the RK15) was a variant of the RK11-D which supported 18-bit data; it was used with the [[PDP-15]]. It used the same cards as the RK11-D, with a jumper selection for 18-bit operation, and a different clock crystal.

It was used with the [[UNICHANNEL 15 System|UC15 Unichannel]], which used a PDP-11 (usually a [[PDP-11/05]]) acting as a slave to the PDP-15; the RK11-E was plugged into the UNIBUS on the PDP-11.

It used the two [[UNIBUS parity]] lines for the two extra data bits on the 18-bit PDP-15. The two extra bits were not used by the PDP-11 or its memory, but went straight through the [[MX15-B Memory Multiplexer]], directly to the PDP-15's [[main memory]].

==RKV11-D==

[[Image:RKV11-D.jpg|200px|thumb|right|RKV11-D card cage and [[H780]] power supply]]

The RKV11-D is a variant of the RK11-D for the QBUS (the others are all UNIBUS).

It uses three of the four quad cards of the RK11-D (M7254-6), along with a replacement fourth card (M7268), in a different custom 4 slot quad-high system unit backplane. The M7268 is connected via two pairs of [[flat cable]]s to two dual cards, one of which (M7269) plugs into a QBUS backplane slot, and the other (M993-YA) into the first RK05 drive. The RKV11-D is mounted in a [[BA11-M]] style mounting box with [[H780]] power supply. The [[BA11-M]] front panel is replaced with an expansion box front panel, with a single indicator for '''DCOK'''.

It is program compatible with the RK11-D, except that it only supports [[Q16]] QBUS mode when writing data. The two extended memory bits in the CSR have no effect; they may be read and written, but are not connected to anything.

==Device registers==

{| border=1
! Register !! Abbreviation !! Address
|-
|Drive Status Register || RKDS || 777400
|-
|Error Register || RKER || 777402
|-
|Control Status Register || RKCS || 777404
|-
|Word Count Register || RKWC || 777406
|-
|Current Bus Address Register || RKBA || 777410
|-
|Disk Address Register || RKDA || 777412
|-
|Maintenance Register || RKMR || 777414
|-
|Data Buffer Register || RKDB || 777416
|}

===777400: Drive Status Register (RKDS)===

{{16bit-header}}
| colspan=3 | Drive ID || DPL || RK05 || DRU || SIN || SCOK || DRY || R/W/S Ready || WPS || SC=CA || colspan=4 | Sector Counter
{{16bitoctal-bitout}}

Note that in the '''''diagram''''' of this register in the 'peripherals handbook' (both 1975 and 1976 editions), bits 7 and 6 are labelled incorrectly; the ''table'' which lists the bits has them correctly.

(To confirm this, consult the RK11-D print set, M7254 page 3; the dual 4->1 muxes which fill this page are the source of the RKDS, RKER, etc registers.)

The name of bit 6 has changed slightly from the RK11-C to the -D ("Access Ready" to "R/W/S Ready"), but it seems to be basically the same functionality.

===777402: Error Register (RKER)===

{{16bit-header}}
| DRE || OVR || WLO || SKE || PGE || NXM || DLT || RTE || NXD || NXC || NXS || colspan=3 | || CSE || WCE
{{16bitoctal-bitout}}

===777404: Control Status Register (RKCS)===
{{16bit-header}}
| ERR || H.E. || SCP || M || IBA || FMT || R/WA || SSE || RDY || IDE || colspan=2 | EX. MEM || colspan=3 | FUNCTION || GO
{{16bitoctal-bitout}}

Bit 9 is"Read/Write All" in the RK11-C, and unused in the -D; bit 12 is "Maint" in the -C, and unused in the -D.

{| class="wikitable"
! Command !! Code || In CSR
|-
| Reset Controller || 0 || 0
|-
| Write || 1 || 02
|-
| Read || 2 || 04
|-
| Write Check || 3 || 06
|-
| Seek || 4 || 010
|-
| Read Check || 5 || 012
|-
| Reset Drive || 6 || 014
|-
| Write Lock || 7 || 016
|}

===777406: Word Count Register (RKWC)===
{{16bit-header}}
| colspan=16 | WC15 <---> WC00
{{16bitoctal-bitout}}

===777410: Current Bus Address Register (RKBA)===
{{16bit-header}}
| colspan=15 | BA15 <---> BA01 || Unused
{{16bitoctal-bitout}}

===777412: Disk Address Register (RKDA)===
{{16bit-header}}
| colspan=3 | DRIVE SELECT || colspan=8 | CYLINDER ADDRESS || SUR || colspan=4 | SECTOR ADDRESS
{{16bitoctal-bitout}}

===777414: Maintenance Register (RKMR)===
{{16bit-header}}
| M. RCP || M. RDP || M. SPS || M. ADA || M. LAI || colspan=3 | || M. DRY || M. R/W/S || colspan=2 | || colspan=4 | MAINT. SECTOR COUNTER
{{16bitoctal-bitout}}

This register is not present in the RK11-D; it reads as 0, and writes to it are discarded.

===777416: Data Buffer Register (RKDB)===
{{16bit-header}}
| colspan=16 | DB15 <---> DB00
{{16bitoctal-bitout}}

==PDP-11 bootstraps==

===Disk 0===

{| border=1
! Address !! Data !! Mnemonic !! Description
|- style="background-color: #ccccdd;"
|1000||012700||MOV #177406,R0 ||Move the address of the Word Count register into R0
|- style="background-color: #ccccff;"
|1002||177406|| || (constant)
|- style="background-color: #ccccdd;"
|1004||012710||MOV #177400,(R0) ||Move block size (negative) into Word Count register
|- style="background-color: #ccccff;"
|1006||177400|| || (constant)
|- style="background-color: #ccccdd;"
|1010||012740||MOV #5,-(R0) ||Move 'Read Go' command into CSR
|- style="background-color: #ccccff;"
|1012||000005|| || (constant)
|- style="background-color: #ccccdd;"
|1014||105710||TSTB (R0) ||Test for 'Done' bit in CSR
|- style="background-color: #ccccff;"
|1016||100376||BPL 1014 ||Jump backward if not set
|- style="background-color: #ccccdd;"
|1020||005007||CLR PC ||Start loaded bootstrap with jump to 0
|}

Note that the INIT pulse caused by hitting the 'Start' button will clear the Bus Adddress register, so the loaded block will be placed at location 0.

===Disk ''n''===

This bootstrap will boot from any disk in a daisy-chained multi-drive configuration. Memory location octal 1006 contains the unit number, as follows:
<table>
<tr>
<td>
{| border=1
! Address !! Data !! Mnemonic !! Description
|- style="background-color: #ccccdd;"
| 1000 || 012700 || MOV #177406, R0 || Store the address of the Word Count register in r0
|- style="background-color: #ccccff;"
| 1002 || 177406 || (constant) || (Which is 177406)
|- style="background-color: #ccccdd;"
| 1004 || 012760 || MOV xxxxxx, 000004(R0) || Store the disk ID number in the Disk Address register
|- style="background-color: #ccccff;"
| 1006 || xxxxxx || (disk ID number) || The disk number goes here.
|- style="background-color: #ccccdd;"
| 1010 || 000004 || (index) ||
|- style="background-color: #ccccff;"
| 1012 || 012700 || MOV #177406, R0 || Store the addresss of the Word Count register in r0
|- style="background-color: #ccccdd;"
| 1014 || 177406 || (constant) || (Which is 177406)
|- style="background-color: #ccccff;"
| 1016 || 012710 || MOV #177400, (R0) || Store 177400 into the Word Count register,
|- style="background-color: #ccccdd;"
| 1020 || 177400 || (constant) || meaning that octal 400 words are to be read.
|- style="background-color: #ccccff;"
| 1022 || 012740 || MOV #000005, -(R0) || Store 5 into the Control Status register
|- style="background-color: #ccccdd;"
| 1024 || 000005 || (constant) || selecting the function "read" with 4, and "go" with 1
|- style="background-color: #ccccff;"
| 1026 || 105710 || TSTB (R0) || Test the Control Status Register (upper) byte
|- style="background-color: #ccccdd;"
| 1030 || 100376 || BPL *-1 || Repeat if it's positive, that is Control Ready is cleared
|- style="background-color: #ccccff;"
| 1032 || 005007 || CLR PC || If not, clear the Program Counter (essentially, jump to 0)
|}
</td>
<td>
{| border=1
! Value !! Unit
|- style="background-color: #ccccdd;"
| 020000 || Unit 1
|- style="background-color: #ccccff;"
| 040000 || Unit 2
|- style="background-color: #ccccdd;"
| 060000 || Unit 3
|- style="background-color: #ccccff;"
| 100000 || Unit 4
|- style="background-color: #ccccdd;"
| 120000 || Unit 5
|- style="background-color: #ccccff;"
| 140000 || Unit 6
|- style="background-color: #ccccdd;"
| 160000 || Unit 7
|}
</td>
</tr>
</table>

==External links==

* [http://www.bitsavers.org/www.computer.museum.uq.edu.au/pdf/DEC-11-HRKDA-B-D%20RK11D%20and%20RK11-E%20Moving%20Head%20Disk%20Drive%20Controller%20Manual.pdf RK11-D and RK11-E moving head disk drive controller manual] (DEC-11-HRKDA-B-D)
* [http://www.bitsavers.org/www.computer.museum.uq.edu.au/pdf/EK-RK11D-OP-001%20RK11-D%20and%20RK11-E%20Moving%20Head%20Disk%20Drive%20Controller%20User's%20Manual.pdf RK11-D and RK11-E moving head disk drive controller user's manual] (EK-RK11D-OP-001)
* [http://www.bitsavers.org/pdf/dec/unibus/RK11-D/EK-RK11D-MM-002.pdf RK11-D and RK11-E moving head disk drive controller manual] (EK-RK11D-MM-002)
* [http://www.bitsavers.org/pdf/dec/qbus/RKV11-D/EK-RKV11-OP-001_RKV11-D_Disk_Drive_Controller_Users_Manual_Jul1977.pdf RKV11-D disk drive controller user's manual] (EK-RKV11-0P-001)
* [http://www.bitsavers.org/pdf/dec/unibus/RK11-D/RK11-D_RevP_Engineering_Drawings_Oct75.pdf RK11-D disk drive controller engineering drawings] (Rev P, 10-1975)
* [http://www.bitsavers.org/pdf/dec/unibus/RK11-D/RK11-D_RevR_Engineering_Drawings_Oct76.pdf RK11-D Engineering Drawings] (Rev R, 10-1976)
* [http://www.bitsavers.org/pdf/dec/unibus/RK11-D/RK11-D_ECOs.pdf RK11-D ECOs]

==Further reading==

* ''RKV11-D disk drive controller technical manual'' (not available online, but in fiche - EP-RKV11-TM-001)
* ''RKV11-D Field Maintenance Print Set (MP00223)'' (not available online)

[[Category: UNIBUS Storage Controllers]]
[[Category: QBUS Storage Controllers]]
[[Category: DEC Documentation Errors]]

DX11-B System 360/370 Channel to PDP-11 Unibus Interface

2026-10-05T15:03:00Z

Jnc: /* External links */ Bitsavers has reorganized a bit

The '''DX11-B System 360/370 Channel to PDP-11 Unibus Interface''' connects a [[UNIBUS]] [[PDP-11]] to an [[IBM I/O channel]] (selector, multiplexer or block multiplexer [[channel]]) on an [[IBM System/360|IBM 360]] or [[IBM System/370|370]] or compatible machine. On the PDP-11 side, [[Direct Memory Access|DMA]] is used to transfer data.

With appropriate software on the PDP-11, it can emulate (from the point of view of the 360/370) either a 2848 display, or a 2703 or 3705 communications controller.

Like many of the early large [[device controller]]s for the PDP-11, it was a large custom [[wire-wrap]]ped [[backplane]] bolted into the front of a 6' tall 19" inch [[H960 rack]]; into it plugged a large number of small M-Series [[FLIP CHIP]]s. A [[power supply]] and a [[DEC indicator panel]] also mount into the rack.

{{semi-stub}}

==See also==

* [[DX20 Programmed Device Adapter]]

==External links==

* [http://www.bitsavers.org/pdf/dec/unibus/DX11-B/DX11-B_PDP-11_to_IBM_360_370_Channel_Interface_Option_Bulletin_1975.pdf DX11B PDP-11 to IBM 360/370 Channel Interface Option Bulletin]
* [http://www.bitsavers.org/pdf/dec/unibus/DX11-B/DEC-11-HDXBA-B-D_DX11-B_Maint_Jul73.pdf DX11-B system 360/370 channel to PDP-11 unibus interface maintenance manual] (DEC-11-HDXBA-B-D)
* [http://www.bitsavers.org/pdf/dec/unibus/DX11-B/EK-DX11AB-MM-002_DX11-B_System_360_370_Channel_to_PDP-11_Unibus_Interface_Maintenance_Manual_Jan76.pdf DX11-8 system 360/370 channel to PDP-11 unibus interface maintenance manual] (EK-DX11AB-MM-002)
* [http://www.bitsavers.org/pdf/dec/unibus/DX11-B/DX11-B_RevP_Engineering_Drawings_Oct74.pdf DX11-B engineering drawings] (Revision P, 10-1974)
* [http://www.bitsavers.org/pdf/dec/unibus/DX11-B/DX11-B_RevAA_Engineering_Drawings_Nov77.pdf DX11-B Engineering Drawings] (Revision AA, 11-1977)
* [http://www.bitsavers.org/pdf/dec/unibus/5408458_ind_panel/dx11.jpg DX11] - DX11 indicator panel (image)
* [http://www.bitsavers.org/pdf/dec/unibus/5408458_ind_panel/dx11ind.jpg DX11] - DX11 indicator panel (captioned diagram)

[[Category: UNIBUS Machine Interfaces]]

DEC indicator panel

2026-10-05T14:17:02Z

Jnc: /* External links */ Bitsavers has reorganized a bit

[[Image:RF11indicator.jpg|thumb|right|150px|[[RF11 disk controller|RF11]] indicator panel mounted, as usual, at the top of an [[H960 rack|H960 cabinet]]]]

'''Indicator panels''', containing arrays of lights which provided information about the internal state of the machine, were provided by [[Digital Equipment Corporation|DEC]] for their earlier computers (such as the [[KA10]]), in common with the other computers of the day. Not only the [[Central Processing Unit|CPU]] had such lights; other devices such as [[disk]] [[device controller|controllers]] also had their own indicator panels.

This tradition lasted through the early models of the [[PDP-8 family|PDP-8]] and [[PDP-11]], although the PDP-11 CPU light displays were modest compared to earlier CPUs. The earliest PDP-11 disk controllers were very much a match for the earlier machines, though, and included indicator panels which displayed a great deal of information.

Alas, the cost of such displays was high, and they were dropped from later controllers. (The only PDP-11 controllers with indicator panels were the [[RF11 disk controller|RF11]], the [[RP11 disk controller|RP11]], and the [[DX11-B System 360/370 Channel to PDP-11 Unibus Interface|DX11]]; the [[RK11-C disk controller|RK11-C]] was wired for one, but DEC never even produced the 'inlay' - a clear plastic panel, with black paint with holes for the lights on the back, and white caption lettering on the front - for it. This was likely connected to the fact that these controllers were the only ones built out of a large number of small [[FLIP CHIP]]s in a large custom [[backplane]].) This was a significant loss; in addition to helping with debugging (both hardware and software issues), they gave an extensive insight into how the machine was operating.

==Details==

[[Image:DX11IndicatorPanel.jpg|thumb|left|300px|Indicator panel from a [[DX11-B System 360/370 Channel to PDP-11 Unibus Interface|DX11]]]]

PDP-10 devices which used a 19 inch rack, along with the few types of PDP-10 [[main memory]] which came in such racks, used a standard indicator panel. The panel provided 4 rows of 36 lights each (although not all were used; unused lights were simply not wired up). Only the inlay was customized to the particular device.

The PDP-8 and PDP-11, although not 36-bit machines, also used the same indicator panel, but in general did not include any 36-bit fields. (The exception is the RP11, which was able to read packs written on a PDP-10, and thus included a 36-bit shift register, which was displayed on the RP11-C panel.)

The 18-bit [[PDP-15]] also used this indicator panel.

The two groups differed in the white bezel; in the PDP-10's, the bezel is metal, and goes over the inlay; in the PDP-11's, the bezel is plastic, and the inlay is laid into the bezel.

Limited engineering drawings (they do not include the full mechanical drawings) for this indicator panel are included in the RF11 Engineering Drawings set; the indicator panel is shown on pp. 186-190. Of particular interest are the parts lists, which include all the inlays extant as of the date of the drawings (10/1972).

==See also==

* [[Front panel]]

==External links==

* [http://www.bitsavers.org/pdf/dec/unibus/RF11/RF11_EngrDrws_Oct70.pdf RF11/RS11 DECdisk system engineering drawings] - contains the engineering drawings for the indicator panel (on pp. 186-190 of the PDF)
* [http://ana-3.lcs.mit.edu/~jnc/tech/DECIndicatorPanels.html Digital Equipment Corporation Indicator Panels] - Includes images of many of the panels
* [http://www.bitsavers.org/pdf/dec/unibus/5408458_ind_panel/back.jpg Image of back] - includes mounting hardware
* [http://www.bitsavers.org/pdf/dec/unibus/5408458_ind_panel/front.jpg Image of front] - includes cables and paddle cards

[[Category: Digital Equipment Corporation]]

RC11 disk controller

2026-10-05T14:14:48Z

Jnc: /* External links */ Bitsavers has reorganized a bit

The '''RC11''' [[device controller]] for the [[UNIBUS]] is a very early [[secondary storage]] controller for the [[PDP-11]]. It can handle up to 4 [[RS64 disk drive|RS64]] [[fixed-head disk]] drives, each with a capacity of 128 Kbytes of storage, organized in 32-word blocks.

The contents of each block are protected by a [[Cyclic redundancy check|CRC]].

==Device registers==

{| border=1
! Register !! Abbreviation !! Address
|-
|Look Ahead Register || RCLA || 777440
|-
|Disk Address Register || RCDA || 777442
|-
|Disk Error Status Register || RCER || 777444
|-
|Disk Control and Status Register || RCCS || 777446
|-
|Word Count Register || RCWC || 777450
|-
|Current Address Register || RCCA || 777452
|-
|Maintenance Register || RCMN || 777454
|-
|Data Buffer Register || RCDB || 777456
|}

===777440: Look Ahead Register (RCLA)===
{{16bit-header}}
| Bad Address || colspan=2 | Unused || colspan=2 | Unit Number || colspan=5 | Track Number || colspan=6 | Sector Address
{{16bitoctal-bitout}}

===777442: Disk Address Register (RCDA)===
{{16bit-header}}
| colspan=3 | Unused || colspan=2 | Unit Number || colspan=5 | Track Number || colspan=6 | Sector Address
{{16bitoctal-bitout}}

===777444: Disk Error Status Register (RCES)===
{{16bit-header}}
| Data Late || Block Check || Data Sync || NXM || colspan=2 | Unused || Timing Track || Unused || Address Parity || Sync Address || Disk Overflow || Missed Xfer || colspan=4 | Unused
{{16bit-bitout}}

===777446: Disk Control and Status Register (RCCS)===
{{16bit-header}}
| Special Condition || Data Error || Address Error || Write Lock || NXD || Write Check || Inhibit Address || Abort || Ready || Interrupt Enable || colspan=2 | Ext Mem || Mode || colspan=2 | Function || Go
{{16bit-bitout}}

===777450: Word Count Register (RCWC)===
{{16bit-header}}
| colspan=16 | WC15 <---> WC00
{{16bitoctal-bitout}}

===777452: Current Address Register (RCCA)===
{{16bit-header}}
| colspan=15 | BA15 <---> BA01 || Unused
{{16bitoctal-bitout}}

===777454: Maintenance Register (RCMN)===
{{16bit-header}}
| colspan=4 | Unit Select || Write Enable || Word Count || DMA Request || Address Found || Clock Polarity || DMA Enable || Data Track || Address Track || Phase Lock || Address Mark || Data Mark || Clock Track
{{16bit-bitout}}

===777456: Data Buffer Register (RCDB)===
{{16bit-header}}
| colspan=16 | DB15 <---> DB00
{{16bitoctal-bitout}}

==Implementation==

The RC11 is composed of a number of [[printed circuit board|boards]] (three [[DEC card form factor|quad]], 5 single) mounted in a 4-slot [[system unit]] [[backplane]]. The quad cards are:

* M7219 - Bus Interface
* M7221 - Disk Interface
* M7222 - Status Control

Single:

* M7220 - Clock Control
* M7224 - Unit and Track Selector
* M7225 - Status Control Extender
* M796 - UNIBUS Master Control
* [[M782 Interrupt Control]]

==External links==

* [http://www.bitsavers.org/pdf/dec/unibus/RC11/DEC-11-HRCA-D_RC11_disc_control_manual.pdf RC11 disk control manual] (DEC-11-HRCA-D)
* [http://www.bitsavers.org/pdf/dec/unibus/RC11/RC11_RevB_Engineering_Drawings_Nov71.pdf RC11 engineering drawings]

[[Category: UNIBUS Storage Controllers]]

RF11 disk controller

2026-10-05T14:12:02Z

Jnc: /* External links */ Bitsavers has reorganized a bit

The '''RF11''' [[device controller]] from [[Digital Equipment Corporation|DEC]] for the [[UNIBUS]] is an early [[secondary storage]] controller for the [[PDP-11]]. It can interface with up to eight [[RS11 disk drive|RS11]] [[fixed-head disk]] drives; each has a capacity of 512 Kbytes of storage.

Unlike all other DEC disk controllers, the RF11 can read or write individual words; this was itended to allow optimal use of both disk space and [[main memory]] (e.g. during [[swapping]]).

Like many of the early large [[peripheral]] controllers for the [[PDP-11]], it was a large custom [[wire-wrap]]ped [[backplane]] which bolted into the front of a 19 inch rack, such as an [[H960 rack|H960]]; into it plugged about 40 small M-Series [[FLIP CHIP]]s.

A single rack held the controller, its [[power supply]], and one or more drives (up to two in that rack), along with an [[DEC indicator panel|indicator panel]] at the top of the rack.

==Device registers==

{| border=1
! Register !! Abbreviation !! Address
|-
|Disk Control Status Register || DCS || 777460
|-
|Word Count Register || WC || 777462
|-
|Current Memory Address || CMA || 777464
|-
|Disk Address Register || DAR || 777466
|-
|Disk Address Extension Error Register || DAE || 777470
|-
|Data Buffer Register || DBR || 777472
|-
|Maintenance Register || MA || 777474
|-
|Address of Disk Segment Register || ADS || 777476
|}

===777460: Disk Control Status Register (DCS)===
{{16bit-header}}
| Error || Freeze || Write Check || Data Parity || NXD || Write Lockout|| Missed Xfer || Disk Clear || Control Ready || Interrupt Enable || colspan=2 | Ext Mem || Maintenance || colspan=2 | Function Register || Go
{{16bit-bitout}}

===777462: Word Count Register (WC)===
{{16bit-header}}
| colspan=16 | WC15 <---> WC00
{{16bitoctal-bitout}}

===777464: Current Memory Address Register (CMA)===
{{16bit-header}}
| colspan=15 | BA15 <---> BA01 || Unused
{{16bitoctal-bitout}}

===777466: Disk Address Register (DAR)===
{{16bit-header}}
| colspan=5 | Track Address || colspan=11 | Word Address
{{16bitoctal-bitout}}

===777470: Disk Address Extension Error Register (DAR)===
{{16bit-header}}
| Address Parity || colspan=3 | Timing Track Error || Unused || NXM || Unused || Current Memory || Data Req Late || Unused || Disk Addr Ovflo || colspan=3 | Disk Address || colspan=2 | Track Address
{{16bit-bitout}}

The low five bits of this register are actually an extension to the Disk Address Register (above).

===777472: Data Buffer Register (DBR)===
{{16bit-header}}
| colspan=16 | DB15 <---> DB00
{{16bitoctal-bitout}}

===777474: Maintenance Register (MA)===
{{16bit-header}}
| colspan=3 | Unused || Data || colspan=3 | Timing || Unused || colspan=2 | Data Track || colspan=2 | Timing C || colspan=2 | Timing B || colspan=2 | Timing A
{{16bit-bitout}}

===777476: Address of Disk Segment Register (ADS)===
{{16bit-header}}
| colspan=5 | Unused || colspan=11 | Disk Segment Address
{{16bitoctal-bitout}}

==External links==

* [http://www.bitsavers.org/pdf/dec/unibus/RF11/DEC-11-HRFB-D__RF11_RS11_DECdisk_System_Manual__Aug71.pdf RF11/RS11 DECdisk system manual] (DEC-11-HRFB-D)
* [http://www.bitsavers.org/www.computer.museum.uq.edu.au/pdf/DEC-11-HRFD-D%20RF11%20&%20RS11%20DECdisk%20System%20Manual.pdf RF11/RS11 DECdisk system manual] (DEC-11-HRFD-D)
* [http://www.bitsavers.org/pdf/dec/unibus/RF11/RF11_EngrDrws_Oct70.pdf RF11/RS11 DECdisk system engineering drawings]

[[Category: UNIBUS Storage Controllers]]

M9301 ROM

2026-10-05T14:09:47Z

Jnc: /* External links */ Bitsavers has reorganized a bit

[[Image:M9301.jpg|250px|thumb|right|M9301 card]]

The '''M9301 ROM''' card was a [[UNIBUS]] [[Read-only memory|ROM]] card for the [[PDP-11]] series of computers. It contained 512 words of memory, all readable directly from the UNIBUS (i.e. not windowed). A [[Dual Inline Package|DIP]] switch bank provided configuration. The M9301 also provided [[terminator|termination]] for the UNIBUS.

It was a [[DEC card form factor|dual]] format card, intended for use in the [[DEC edge connector contact identification|two top (AB) connectors]] of a [[Modified UNIBUS Device|MUD]] slot, or in a UNIBUS in/out slot.

Most versions were used for [[bootstrap|bootstrapping]] the machine, from [[disk]], [[paper tape]], [[magnetic tape]], etc, but it could be use for any purpose; most [[Digital Equipment Corporation|DEC]]-supplied pre-programmed versions included a console emulator, and basic [[diagnostic]]s. A command to boot the machine could be given in the emulator, using a symbolic [[DEC bootstrap device codes|device code]].

It used four 4-bit wide [[PROM]]s to hold the data. The board occupied [[address]]es 773000-773776 and 765000-765776; a configuration switch allowed the lower block to be disabled.

Other configuration switches controlled which address the [[Central Processing Unit|CPU]] jumped to on power on (a clever kludge, controlled by another configuration switch, allowed the board to force the CPU to read its power-on [[Program Counter|PC]] and [[Processor Status Word|PS]] from the ROM, at a location set by still other configuration switches, thereby allowing auto-boot on power-on).

The board came in several main variants, designated M9301-Yx (where 'x' is a capital letter, starting with 'A') came pre-programmed from DEC to perform various functions.

There were two different etch revisions of the card itself, but they seem to be programming-wise identical.

==Configuration switches==

The board contains a single 10-switch DIP switch, S1, which controls the board's behaviour.

If S1-1 is set to 'off' (open), the low bank of memory on the card (765000-765777) is disabled; when 'on' (closed) it is enabled.

If S1-2 is 'off', the system will power-up normally; if 'on', the CPU will obtain its new PC/PS pair from locations 173024 on the card, which contain a mixture of bits from the ROM (high bits) and the configuration switch (low bits), which can be used to force the CPU to start executing in the ROM on power-on. (This is done by asserting the appropriate high address lines on the UNIBUS for the first two bus cycles after power-up; a technique pioneered by the [[BM873 ROM]].)

Switches S1-3 through S1-10 contain bits 8 through 1 of the power-on PC (above); the exact meaning will depend on the board variant (below).

==Connector tabs==

The board contains three connector tabs, which may be used with external switches, to control the board's behaviour.

One, TP3, is a [[ground return]]. TP2, when momemtarily grounded, forces the machine to execute a power-fail/restart sequence (by asserting UNIBUS line ACLO). TP1, when grounded, forces the machine to execute the on-board ROM on power on, no matter what the position of S1-2 (above).

==Variants==

* M9301-YA - (ROMs 034A9, 035A9, 036A9, 037A9) - [[PDP-11/04]] and [[PDP-11/34]] [[Original Equipment Manufacturer|OEM]] version; had basic diagnostics, console emulator, booted from various devices ([[RK11 disk controller|RK11]] and [[RP11 disk controller|RP11]] disks, [[TC11]] [[DECtape]], [[TM11]] magnetic tape, serial line, [[PC11]] high-speed paper-tape reader, [[TA11]] casette tape, [[RX11 floppy disk controller|RX11]] 8-inch [[floppy disk]]), supported auto-boot on power on, and also power-fail restart

* M9301-YB - (ROMs 038A9, 039A9, 040A9, 041A9) - /04 and /34 end user version; had basic diagnostics, console emulator, booted from various devices (RK11, RP11, TC11, TM11, TA11, RX11, serial line, high-speed paper-tape reader, RJS, RJP, TJU), also power-fail restart

* M9301-YC - [[PDP-11/70]] version; contained basic CPU, cache and memory diagnostics, booted from various devices (TM11, TC11, RK11, RP11, [[RK611 disk controller|RK611]], RJS, RJP, TJU, RX11)

* M9301-YD - All models; contained code to allow a terminal attached to the machine to be a terminal on some other line; also had boot code for RX11 and [[DDCMP]]

* M9301-YE - All models; had basic diagnostics, console emulator; booted from low speed paper tape or [[DECnet]]; supported auto-boot on power on, and also power-fail restart

* M9301-YF - (ROMs 480A9, 481A9, 482A9, 483A9) - All models (auto-start not available on [[PDP-11/45]], [[PDP-11/50]]); had basic diagnostics, console emulator, booted from various devices (RK11, RK06, RP11, TC11, TM11, TA11, RX11, serial line, high-speed paper-tape reader, RJS, RJP, TJU), supported auto-boot on power on, and also power-fail restart

* M9301-YH - (ROMs 332A9, 333A9, 334A9, 335A9) - /60 and /70 version; contained basic CPU, cache and memory diagnostics, booted from various devices (TM11, TC11, RK11, RP11, RK06, RJS, RJP, TJU, RX11, high-speed paper-tape reader)

* M9301-YJ - All models; had basic diagnostics, console emulator; booted from DECnet, and various devices (RX11, TU, serial line, DMC), also power-fail restart

==Entry points==

DEC ROM programs can be started manually, on machines with a front panel which allow that. Useful entry points (all in octal) are given here.

===M9301-YA===

{| class="wikitable"
! Location !! Function
|-
| 173000 || Console emulator w/ CPU Diagnostics
|-
| 173002 || Diagnostics, then emulate power-fail restart trap through 24
|-
| 173030 || Console emulator (no diagnostics)
|-
| 173440 || RK11 Boot w/ Diagnostics
|-
| 173442 || RK11 Boot (no diagnostics)
|-
| 173466 || RP11 Boot w/ Diagnostics
|-
| 173470 || RP11 Boot (no diagnostics)
|-
| 173506 || TC11 Boot w/ Diagnostics
|-
| 173570 || TC11 Boot (no diagnostics)
|-
| 173524 || TM11 Boot w/ Diagnostics
|-
| 173526 || TM11 Boot (no diagnostics)
|-
| 173624 || TA11 Boot w/ Diagnostics
|-
| 173626 || TA11 Boot (no diagnostics)
|-
| 173636 || RX11 Boot w/ Diagnostics
|-
| 173640 || RX11 Boot (no diagnostics)
|-
| 173650 || DL11 Boot w/ Diagnostics
|-
| 173652 || DL11 Boot (no diagnostics)
|-
| 173660 || PC11 Boot w/ Diagnostics
|-
| 173662 || PC11 Boot (no diagnostics)
|}

Note that switch S1-1 must be on for all the choices ''with'' diagnostics.

===M9301-YB===

{| class="wikitable"
! Location !! Function
|-
| 173000 || Console emulator w/ CPU Diagnostics
|-
| 173002 || Diagnostics, then emulate power-fail restart trap through 24
|-
| 173226 || Console emulator (no diagnostics)
|}

===M9301-YF===

{| class="wikitable"
! Location !! Function
|-
| 165404/173000* || Console emulator w/ CPU Diagnostics
|-
| 165406/173002* || Console emulator (no diagnostics)
|-
| 173040 || RP11 Boot w/ Diagnostics
|-
| 173042 || RP11 Boot (no diagnostics)
|-
| 173054 || TU16 Boot w/ Diagnostics
|-
| 173056 || TU16 Boot (no diagnostics)
|-
| 173144 || RK11 Boot w/ Diagnostics
|-
| 173146 || RK11 Boot (no diagnostics)
|-
| 173174 || TC11 Boot w/ Diagnostics
|-
| 173176 || TC11 Boot (no diagnostics)
|-
| 173224 || RP04/5/6 w/ Diagnostics
|-
| 173226 || RP04/5/6 Boot (no diagnostics)
|-
| 173364 || DL11 Boot w/ Diagnostics
|-
| 173366 || DL11 Boot (no diagnostics)
|-
| 173440 || RS03/4 Boot w/ Diagnostics
|-
| 173442 || RS03/4 Boot (no diagnostics)
|-
| 173474 || TM11 Boot w/ Diagnostics
|-
| 173476 || TM11 Boot (no diagnostics)
|-
| 173544 || RX11 Boot w/ Diagnostics
|-
| 173546 || RX11 Boot (no diagnostics)
|-
| 173644 || Diagnostics, then emulate power-fail restart trap through 24
|-
| 173646 || Emulate power-fail restart trap through 24
|-
| 173662 || RK611 Boot w/ Diagnostics
|-
| 173664 || RK611 Boot (no diagnostics)
|-
| 173704 || PC11 Boot w/ Diagnostics
|-
| 173706 || PC11 Boot (no diagnostics)
|}

Note that switch S1-1 must be on for all the choices ''with'' diagnostics, and also the console emulation and power-fail restart choices.

''*'' - The manual gives the 16540x locations for manual start locations, but the configuration DIP switch settings correspond to the 17300x locations.

==See also==

* [[UNIBUS boot ROMs]]

==External links==

* [http://www.bitsavers.org/pdf/dec/unibus/M9301/EK-M9301-TM-001_M9301_Bootstrap_Terminator_Module_Maintenance_and_Operators_Manual_Jun77.pdf M9301 bootstrap/terminator module maintenance and operator's manual] (EK-M9301-TM-001)
* [http://www.bitsavers.org/pdf/dec/unibus/M9301/M9301_RevV_Engineering_Drawings_Dec77.pdf UNIBUS Terminator/Bootstrap Engineering Drawings]
* [http://ana-3.lcs.mit.edu/~jnc/tech/pdp11/ROMs/M9301-YA.mac Disassembled and commented M9301-YA ROM code]
* [http://ana-3.lcs.mit.edu/~jnc/tech/pdp11/ROMs/M9301-YB.mac Disassembled and partially commented M9301-YB ROM code]
* [http://ana-3.lcs.mit.edu/~jnc/tech/pdp11/ROMs/M9301-YF.mac Disassembled and partially commented M9301-YF ROM code]
* [http://ana-3.lcs.mit.edu/~jnc/tech/pdp11/ROMs/M9301-YH.mac Disassembled but mostly un-commented M9301-YH ROM code]

[[Category: UNIBUS ROMs]]

DHQ11 asynchronous serial line interface

2026-10-05T14:05:59Z

Jnc: /* External links */ Bitsavers has reorganized a bit

[[Image:M3107DHQ11.jpg|250px|thumb|right|DHQ11 card]]

The '''DHQ11 asynchronous serial line interface''' is the second [[QBUS]] equivalent to the [[UNIBUS]] [[DH11 asynchronous serial line interface|DH11]] (it is a replacement for the [[DHV11 asynchronous serial line interface|DHV11]]). It provided 8 [[EIA RS-232 serial line interface|RS-232]] [[asynchronous serial line]]s. Output used [[Direct Memory Access|DMA]] (with each line having its own [[buffer]] [[pointer]] and count); input used a 256-character [[First-In First-Out buffer|FIFO buffer]].

It can be set (via a switch) to exactly emulate either a DHV11 or [[DHU11 asynchronous serial line interface|DHU11]].

==Implementation==

Physically, the DHQ11 consisted of a single [[DEC card form factor|dual]] card, the '''M3107''', connected to a pair of H3173-A distribution panels (4 lines each) via a BC05L [[flat cable]], one per distribution panel; the BC05L connects to a 40-pin [[Berg connector|Berg header]] on each end. The H3173-A can be recognized by the [[DEC part number]] 50-15588-01 or -02 on its [[printed circuit board|PCB]]; each contains four male [[EIA RS-232 serial line interface#Connectors|DB-25 connectors]] (DB-25P). In addition to the usual '-xx' length indicators on the BC05L cable, it was also available in BC05L-1K (21 inch) and BC05L-2F (30 inch) lengths.

==Device registers==

The [[register]]s will depend on whether it is emulating a DHV11 or DHU11.

===Control and Status Register (CSR)===

In DHU11 mode, the CSR is:
{{16bit-header}}
| TXA || TXIE || DF || TDE || Unused || colspan=3 | Tx Line || RDA || RXIE || MR || SKIP || Unused || colspan=3 | Line
{{16bitoctal-bitout}}

*TXA - Transmitter Action
*TXIE - Transmit Interrupt Enable
*DF - Diagnostic Fail
*TDE - Transmit DMA Error
*Tx Line - Line which set TXA
*RDA - Received Data Available
*RXIE - Receive Interrupt Enable
*MR - Master Reset
*SKIP - Skip Self-Test
*Line - Select TXC through TBCT

==External links==

* [http://www.bitsavers.org/pdf/dec/qbus/DHQ11/EK-DHQ11-UG-002.pdf DHQ11 User Guide] (EK-DHQ11-UG.002)
* [http://www.bitsavers.org/www.computer.museum.uq.edu.au/pdf/EK-DHQ11-TM-01%20DHQ11%20Technical%20Manual.pdf DHQ11 Technical Manual] (EK-DHQ11-TM-01)
* [http://www.bitsavers.org/pdf/dec/qbus/DHQ11/MP02380_DHQ11_sch_Jul90.pdf Field Maintenance Print Set] (MP02380)
* [http://www.bitsavers.org/www.computer.museum.uq.edu.au/pdf/DHQ11%20Notes.pdf DHQ11 Notes]

[[Category: QBUS Asynchronous Serial Interfaces]]

DRV11-WA General Purpose DMA Interface

2026-10-04T22:41:08Z

Jnc: /* External links */ Bitsavers has reorganized a bit

[[Image:DRV11-WA.jpg|thumb|200px|right|DRV11-WA board]]

The '''DRV11-WA Direct Memory Access Interface''' is a [[parallel interface]] [[device controller]] for the [[QBUS]] which provided a pair of 16-[[bit]] parallel ports, one input, and one output. It uses [[Direct Memory Access|DMA]] to transfer data; it is a [[QBUS#Variable address size|Q22]] device.

It is effectively a [[half-duplex]] device; it has only a single pair of [[bus]] [[address]] and word count [[register]]s. Directional control is by the [[user]]'s device specifying whether each cycle is a DATI, DATO, or DATIO.

It was a [[DEC card form factor|dual]] format card (M7651); connection to the user's device is via a pair of 40-[[pin]] [[Berg connector]]s. For [[diagnostic]] purposes, a BC05L cable can be used to loop the device's input and output together.

==Registers==

The device has six control and [[buffer]] registers, which can be configured to any group of four sequential [[word]] locations in the I/O page (two pairs of registers share an address); the first DRV11-WA is normally configured to addresses 772410-72416.

{| border=1
! Register !! Abbreviation !! Address
|-
|Word Count Register || DRWCR || 767770
|-
|Bus Address Register || DRBAR || 767772
|-
|Bus Address Extension Register || DRBAE || 767772
|-
|Control and Status Register || DRCSR || 767774
|-
|Input Data Buffer Register || DRINBUF || 767776 (read)
|-
|Output Data Buffer Register || DROUTBUF || 767776 (write)
|}

To gain access to the BAE, reference the BAR; this sets an internal flag which sends the next reference to the BAR's address to the BAE. Referring to any register (e.g. reading the WCR) clears the flag. The two buffer registers share an address, responding to read or write cycles as the case might be.



==External links==

* [http://www.vaxhaven.com/images/8/80/EK-DRVWA-UG-001.pdf DRV11-WA General Purpose DMA Interface User's Guide] (EK-DRVWA-UG-001)
* [http://www.bitsavers.org/pdf/dec/qbus/DRV11-W/EK-DRVWA-UG-002_DRV11W_UG.pdf DRV11-WA General Purpose DMA Interface User's Guide] (EK-ORVWA-UG-002)
* [http://www.bitsavers.org/pdf/dec/qbus/DRV11-W/MP01582_DRV11-WA_EngrDrws.pdf DRV11-WA Field Maintenance Print Set] (MP01582-01)

[[Category: QBUS Parallel Interfaces]]

BM792 ROM

2026-10-04T22:35:54Z

Jnc: /* External links */ Bitsavers has reorganized a bit

[[Image:BM792-YA.jpg|300px|thumb|right|M792-YA card]]

The '''BM792 ROM''' card was the first [[UNIBUS]] [[Read-only memory|ROM]] card for the [[PDP-11]] series of computers; it contained only 32 [[word]]s of memory. It was a [[DEC card form factor|quad]] format card, and used an [[Small Peripheral Controller|SPC]] slot. Most versions were used for [[bootstrap]]ping the machine, from [[disk]], [[paper tape|paper]] and [[magnetic tape]], etc, but it could be used for any purpose

It used individual [[diode]]s in an array to represent individual [[bit]]s; if the diode was present, the bit contained a '1'; if the diode was not present, a '0'. [[Jumper]]s allowed the board to occupy any 32-word block from 0773000 to 0773700, so longer programs could be accomodated with multiple cards.

The board came in two main variants: the M792 came fully populated with diodes, and the user removed diodes (either by de-soldering them, or clipping their leads) to produce the desired [[program]]; other variants, designated M792-Yx (where 'x' is a capital letter, starting with 'A') came pre-programmed from DEC to perform various functions.

==Variants==

* BM792-YA - [[Asynchronous serial line|Serial line]] ([[KL11 asynchronous serial line interface|KL11]]/[[DL11 asynchronous serial line interface|DL11]]), high-speed [[paper tape]] reader ([[PC11 High-Speed Paper-Tape Reader/Punch Control|PC11]])
* BM792-YB - [[TC11 DECtape controller|TC11]] [[DECtape]] and disks ([[RC11 disk controller|RC11]], [[RF11 disk controller|RF11]], [[RK11 disk controller|RK11]], [[RP11 disk controller|RP11]])
* BM792-YC - [[CR11 Card Readers|CR11]] [[punched card]] reader
* MR11-DB - A two board set, consisting of the BM792-YD and -YE, it supported the same devices as the -YB, with the addition of the [[TM11 magtape controller|TM11]] [[magnetic tape]]
* BM792-YF - DECtape and RF11 and RK11 disks
* BM792-YH - [[TA11 Magnetic Tape Cassette controller|TA11]] casette magnetic tape
* BM792-YJ - Special TM11 loader
* BM792-YK - Special version for the [[VT20]], using its second serial line
* BM792-YL - [[RX11 floppy disk controller|RX11]] [[floppy disk]] controller

Note that there are two variants of the -YA (see the link below).

==See also==

* [[UNIBUS boot ROMs]]

==External links==

* [http://www.bitsavers.org/pdf/dec/unibus/BM792/DEC-11-HBMAA-E-D_BM792_Read-only-memory_and_MR11-DB_Bootstrap_Loader_Jan75.pdf BM792 read-only-memory and MR11-DB bootstrap loader] (DEC-11-HBMAA-E-D)
* [http://www.bitsavers.org/pdf/dec/unibus/BM792/MR11-DB_64_Word_Bootstrap_M792_May72.pdf MR11-DB bulk storage bootstrap loader engineering drawings]
* [http://ana-3.lcs.mit.edu/~jnc/tech/pdp11/ROMs/M792-YA.mac Dis-assembled and commented dump of M792-YA boot ROMs]
* [http://ana-3.lcs.mit.edu/~jnc/tech/pdp11/ROMs/M792-YK.mac Dis-assembled and commented dump of M792-YK boot ROMs]

[[Category: UNIBUS ROMs]]

DR11-W Direct Memory Access Interface

2026-10-04T22:29:43Z

Jnc: /* External links */ Bitsavers has reorganized a bit

[[Image:DR11-W M8716.jpg|300px|thumb|right|DR11-W card]]

The '''DR11-W Direct Memory Access Interface''' was a [[parallel interface]] for the [[UNIBUS]], one which used [[Direct Memory Access|DMA]] to transfer data to a user device. It was a single [[DEC card form factor|hex]] card (the '''M8716''') replacement for the earlier multi-card [[DR11-B parallel interface]]. The DR11-W is somewhat [[program compatible]] with the DR11-B.

By appropriate manipulation of the control lines (below), the user device can do [[byte]] or [[word]] cycles on the [[bus]], perform read-modify-write bus cycles, or do block 'burst' bus transfers. The DR11-W can also be operated by [[programmed I/O]], potentially via [[interrupt]]s.

Like the DR11-B, the interface between the DR11-W and the user device uses a number of unidirectional control lines (below), which control data transfer; and sets of three 'status' and 'control' lines, which appear in the Status and Command Register. Data going to the user device is [[buffer]]ed in a set of [[latch]]es; data coming from the user device is also buffered, and is sampled and latched when i) the input buffer register (below) is read, or ii) either 'Cycle Request' input [[conductor|line]] is asserted.

The [[register]] [[address]]es, [[interrupt vector]], and other configuration (e.g. the [[polarity]] of the BUSY [[signal]]) are selected by setting [[Dual Inline Package|DIP]] switches on the card.

==Registers==

{| border=1
! Register !! Abbreviation !! Address
|-
|Word Count Register || DRWC || 772410
|-
|Bus Address Register || DRBA || 772412
|-
|Control and Status Register || DRCSR || 772414
|-
|Error and Information Register || DREIR || 772414
|-
|Data Buffer Register || DRDB || 772416
|}

Writes to the CSR/EIR address are always sent to the CSR. The result of a read depends on the setting of the Register Select bit, which is set by a write to the CSR.

The [[address]]es shown are for the first DR11-W in a system; additional ones are normally set to be at 772430, 772450, 772470, etc.

In the register contents (below), bits which are read/write or unused are shown in normal font, those which are read-only are in ''italics'', and write-only in '''bold'''.

===772410: Word Count Register (DRWC)===
{{16bit-header}}
| colspan=16 | WC15 <---> WC00
{{16bit-bitout}}

Bit 0 is read-only, and is provided by the connected user device.

===772412: Bus Address Register (DRBA)===
{{16bit-header}}
| colspan=16 | BA15 <---> BA00
{{16bit-bitout}}

Bit 0 is read-only, and is provided by the connected user device.

===772414: Control and Status Register (DRCSR)===
{{16bit-header}}
| ''ERROR''/'''REGSEL''' || NXM || ATTN || MAINT || colspan=3 | ''STAT A-C'' || CYCLE || ''READY'' || IE || colspan=2 | XBA16-17 || colspan=3 | FUNC1-3 || ''REGSEL''/'''GO'''
{{16bit-bitout}}

===772414: Error and Information Register (DREIR)===
{{16bit-header}}
| ''ERROR'' || ''NXM'' || ''ATTN'' || ''MCR'' || ''ACLO'' || ''PAR'' || ''BRTE'' || ''NBS'' || colspan=7 | Unused || ''REGSEL''
{{16bit-bitout}}

===772416: Data Buffer Register (DRDB)===
{{16bit-header}}
| colspan=16 | Data15 <---> Data00
{{16bit-bitout}}

This is actually a pair of registers; a read-only input buffer register, and a write-only output buffer register.

==Implementation==

Connection to the user's device is via a pair of 40-pin [[Berg connector]] headers, into which [[flat cable]]s (such as BC06R's) plug. For [[diagnostic]] purposes, a BC05L cable can be used to loop the device's input and output together.

Both receivers and drivers are [[single-ended signalling|single-ended]], so for best results the DR11-W and the user's device should share a [[ground]].

==External links==

* [http://www.bitsavers.org/pdf/dec/unibus/DR11-W/DR11W_UsersMan.pdf DR11-W Direct Memory Interface Module User's Guide] (EK-DR11W-UG-001)
* [http://www.bitsavers.org/pdf/dec/unibus/DR11-W/EK-DR11W-UG-004.pdf DR11-W Direct Memory Access Interface Module User's Guide] (EK-DR11W-UG-004)
* [http://www.bitsavers.org/pdf/dec/unibus/DR11-W/MP00693_DR11-W_EngrDrws.pdf DR11-W Field Maintenance Print Set] (MP00693)

[[Category: UNIBUS Parallel Interfaces]]

DL11 asynchronous serial line interface

2026-10-04T22:26:44Z

Jnc: /* External links */ Bitsavers has reorganized a bit

[[Image:M7800DL11E.jpg|300px|thumb|right|DL11-E card]]

The '''DL11 asynchronous serial line interface''' card (M7800) was a [[UNIBUS]] [[peripheral]] for the [[PDP-11]] series of computers which provided a single [[asynchronous serial line]]. It was a [[DEC card form factor|quad]] format card, and used an [[Small Peripheral Controller|SPC]] slot.

It provided both [[20mA current loop serial line interface|20mA]] and (in some versions) [[EIA RS-232 serial line interface|EIA RS-232]] connectivity at speeds of 110 to 9600 [[baud rate|baud]] (the range depended on the version); the DL11-E version also provided full [[modem]] control. Line connection was via a 40-pin [[Berg connector]] header on the top edge of the card, using the standard [[DEC asynchronous serial line pinout]]; [[transistor-transistor logic|TTL]]-level signals were also present on this connector.

It was a functionally identical single-board replacement for the [[KL11 asynchronous serial line interface]], which consisted of a dual card, along with two standard single card [[FLIP CHIP]]s. The DL11 also made use of the then-new [[Universal Asynchronous Receiver/Transmitter|UART]] [[MSI]] [[integrated circuit|chip]].

The [[TU58]] tape drive is connected to a DL11-type device, so the device [[address]], etc for TU58's are as for DL11's - the [[register]] addresses and [[interrupt vector]]s are those given below for the 'first' DL11 (DL11 #1).

==Connection==

Selecting between current-loop and EIA interface inputs is done by loopbacks on the Berg connector, called "interlock".

* The actual input is TTL on pin 'E' (labelled "Serial Input TTL" and "Interlock In")
* The current loop receiver has input on 'K' and 'S', output on 'H' ("20 mA Interlock Out")
* The current loop output is on 'AA' and 'KK'
* (optional) EIA level receiver has input on 'J', output on 'M' ("EIA Interlock Out")
* (optional) EIA output is on 'F'

So, for current loop, we join H to E (and connect K, S, AA, KK to the communicating system). For EIA we join M to E (and connect at least J, F to the other system.) These configurations are normally done in the cable; see the DL11 manual, tables 3-3 to 3-6.

==Programming interface==

The DL11 has 2 device registers for the receive side (one Control and Status Register - CSR - and one data [[buffer]] register), and similarly, two for the transmit side. Each DL11 has two interrupt vectors - again, one receive, and one transmit.

For the PDP-11 main console (which is always a KL11/DL11 compatible device), the 'zeroth' DL11, the standard is that 0777560 is the base address (so the receiver registers are 0777560-2, and the transmitter are 0777564-6), and 060 is the base vector.

The first DL11 after the console is always assigned the address 0776500, and vector 0300. Additional DL11's are assigned addresses and vectors immediately following, for DL11's #1-#16 (i.e. 0776500-676 and 0300-0476).

==Configuration==

The bus address, interrupt vector, and line parameters ([[parity]], number of stop and data bits) were selected by soldered [[jumper]]s; the baud rate was set by a combination of a replaceable crystal (several different ones were standard), and a pair of 10-position dial selectors (one for transmit, one for receive) which selected a rate:

{| class="wikitable"
! Crystal Speed !! 1 !! 2 !! 3 !! 4 !! 5 !! 6 !! 7 !! 8
|-
| 884.8 KHz || 35.7 || 55 || 110 || 220 || 440 || 880 || 1320 || 1760
|-
| 1.033 MHz || 44.8 || 67.3 || 134.5 || 269 || 538 || 1076 || 1614 || 2152
|-
| 1.152 MHz || 50 || 75 || 150 || 300 || 600 || 1200 || 1800 || 2400
|-
| 4.608 MHz || 200 || 300 || 600 || 1200 || 2400 || 4800 || 7200 || 9600
|}

(The 9th and 10th dial selector positions selected external [[clock]] inputs, not divisions of the crystal.)

The address and vector jumpers specify the base of the register bus addresses, and vectors, in binary. On the DL11, it is only possible to set the base of the entire group of 4 registers; the transmit and receive register groups cannot be moved around independently. Similarly for the vector, only the base of the pair of vectors can be configured; the receive (at B) and transmit (at B+4) are paired in the hardware.

The simple rule on the DL11 is that vector jumpers are the inverse of address jumpers: for the vector, jumpers are 'in' for '1', and for the address, they are 'in' for '0'. (This inversion can be a memory jogger - 'Oh, the DL11, that blasted interface where the jumper sense is inverted between address and vector!' Then one only has to look up one of the two.)

Address jumper A3 is the 3rd bit of the address, i.e. the 010 bit, the lowest one that is configurable (the device is a block of 8 bytes, from xxxxx0 to xxxxx7, so it is not possible to set any of the low 3 bits in the base address, they must be 0), and A10 is the highest bit which can be changed. V3 through V8 perform a similar function for the vectors.

The following table shows the bits which are affected when the jumper is '''''in'''''.

{| class="wikitable"
! Address Jumper !! Address Bit !! Vector Jumper !! Vector bit
|-
| A3 || -010 || V3 || +010
|-
| A4 || -020 || V4 || +020
|-
| A5 || -040 || V5 || +040
|-
| A6 || -0100 || V6 || +0100
|-
| A7 || -0200 || V7 || +0200
|-
| A8 || -0400 || V8 || +0400
|-
| A9 || -01000
|-
| A10 || -02000
|}

===Sample configurations===

The following table gives the jumper configuration for the two most common DL11 configurations:
* main console (address 0777560, vector 060)
* 'first' DL11 - often a TU58, now (address 0776500, vector 0300)

{| class="wikitable"
! Jumper !! Bit !! Console !! First DL11
|-
| A3 || 010 || In || In
|-
| A4 || 020 || Out || In
|-
| A5 || 040 || Out || In
|-
| A6 || 0100 || Out || Out
|-
| A7 || 0200 || In || In
|-
| A8 || 0400 || Out || Out
|-
| A9 || 01000 || Out || In
|-
| A10 || 02000 ||Out || Out
|-
| colspan="3" |
|-
| V3 || 010 || Out || Out
|-
| V4 || 020 || In || Out
|-
| V5 || 040 || In || Out
|-
| V6 || 0100 || Out || In
|-
| V7 || 0200 || Out || In
|-
| V8 || 0400 || Out || Out
|}

==Versions==

The DL11 came in 5 versions, -A through -E.

The -A and -C versions (board M7800-YA on at least one of these) were 20mA interface '''only''', and omitted the components necessary for the EIA interface.

The -A and -B apparently did not provide full baud rate selection and selectable data coding (they were restricted to 8-bit data, no parity, and 1 or 2 stop bits); they also could not provide 'split' speeds (differing baud rates on transmit and receive). Apparently, these versions had more limited address selection capability; they could only be configured to 0776XX0, where XX ranged from 050 to 067.

Only the -C through -E could be ordered with the 4th (9600-baud capable) crystal (it is not known whether the earlier ones would work if this crystal were inserted). Only the -E provided full modem control.

The -A and -C versions are easy to identify visually; they are both missing a large number of components (five 14-pin chips including 1488, 1489 which are RS-232 receiver and driver chips).

How to tell the others apart (if, indeed, there is any difference between the -D and -E) is not yet documented.

==See also==

* [[DL11-W serial line unit/real-time clock option]]

==External links==

* [http://www.bitsavers.org/pdf/dec/unibus/DL11/EK-DL11-OP-001_Sep76.pdf DL11 asynchronous line interface user's manual] (EK-DL11-OP-001)
* [http://www.bitsavers.org/pdf/dec/unibus/DL11/EK-DL11-TM-003_DL11_Asynchronous_Line_Interface_Manual_Sep75.pdf DL11 asynchronous line interface manual] (EK-DL11-TM-003) - technical manual
* [http://www.bitsavers.org/pdf/dec/unibus/DL11/DL11_EngrDrws.pdf DL11 asynchronous line interface engineering drawings] - originals
* [http://www.bitsavers.org/pdf/dec/unibus/DL11/DL11_schem_Mar78.pdf DL11 asynchronous line interface engineering drawings] - redrawn
* [https://chdickman.com/pdp11/Notes/DL11.shtml Notes: DEC DL11]

[[Category: UNIBUS Asynchronous Serial Interfaces]]