Computer History Wiki - User contributions [en]

FLIP CHIP

2007-05-18T21:29:59Z

64.107.133.124: /* Flip-Chip families */

{{DEC-HW-stub}}
[[Image:B Series Flip Chip.jpg|thumb|300px|A B series Flip-Chip]]
'''Flip-Chip''' was a [[DEC]] registered trademark, named after the "flipchip" component mounting technique which quite rapidly faded from fame. The name was retained although the majority of Flip-Chips never really were flipchip-mounted as it became apparent that the flipchip mounting technique was highly unreliable. Flip-chips were used in the DEC [[PDP-7]] (Referred to in documentation as the "FLIP CHIP"), [[PDP-8]], [[PDP-9]] and [[PDP-10]], beginning on August 24, 1964.

In practice, they performed generic, simple functions, similar to an integrated circuit. They were approximately 4 inches long and 2.5 inches wide. Each had 36 connectors, 18 on each side.

== Naming ==

There appeared to be some confusion inside DEC at the time, as various manuals refer to it as "FLIP CHIP", "Flip Chip", "FLIP-CHIP", "Flip-Chip" and "Flip Chip", with trademark and registered trademark symbols.

==Flip-Chip families==

[[Image:FlipChips.jpeg|thumb|250px|Flip-chips in different forms and a rainbow of colors, in a [[PDP-8]].]]
The various families were color-coded, and the first letter denoted a color, which was also visible on the handle.

===A series===

The A stands for Amber. The A series were used for analog functions - ADCs, DACs, amplifiers etc.

{|class="wikitable"
|-
| Part Number|| Description
|-
| A123 || Positive logic multiplexer
|-
| A131 || unknown
|-
| A200 || Op. amp.
|-
| A206 || Op. amp.
|-
| A207 || Op. amp.
|-
| A214 || unknown
|-
| A215 || unknown
|-
| A404 || sampler???
|-
| A613 || 12 bit DAC converter
|-
| A615 || unknown
|-
| A618 || 10 bit DAC converter
|-
| A619 || 10 bit DAC converter
|-
| A620 || 10 bit DAC converter
|-
| A621 || 10 bit DAC converter
|-
| A702 || reference supply???
|-
| A704 || reference supply???
|-
| A811 || 10 bit ADC converter
|-
| A990 || amplifier
|-
| A992 || amplifier
|}

===B series===

The B stands for Blue. The B series were used as core logic in the higher-end CPUs.

===G series===

The G stands for Green. The G series were used for "anything with non-standard voltages", I think.

===M series===

The M stands for magenta. Part of this line is simple TTL-level logic, while later on, it became quite complex, see [[list of DEC part numbers]]. They replaced the R series which used discrete transistors with integrated circuits.

* Power supply: 5 V
* Operate at up to 6 MHz

===R series===

The R stands for Red. Slower logic than the B series, but cheaper. Used extensively in the I/O circuitry of computers.

* Slower logic than B series, cheaper
* Used in a variety of systems, e.g. [[PDP-8]]
* Power supply 10 and -15 volts
* Operational to 2 megahertz
* Signal level 0 volts, logic 0 and -3 volts, logic 1
* Typical price $20 to $30

{| class="wikitable"
|-
| Part Number|| Description
|-
| R001 || Diode network
|-
| R002 || Diode network
|-
| R107 || Inverter
|-
| R111 || Expandable NAND/NOR gate
|-
| R113 || NAND/NOR gate
|-
| R121 || NAND/NOR gate
|-
| R122 || NAND/NOR gate
|-
| R123 || Input bus
|-
| R131 || Exclusive OR
|-
| R141 || AND/NOR gate
|-
| R151 || Binary to octal decoder
|-
| R181 || DC carry chain
|-
| R200 || Flipflop
|-
| R201 || Flipflop
|-
| R202 || Dual flipflop
|-
| R203 || Triple flipflop
|-
| R204 || Quadruple flipflop
|-
| R205 || Dual flipflop
|-
| R302 || Dual delay multivibrator
|-
| R303 || Integrating one shot
|-
| R401 || Variable clock
|-
| R405 || Crystal clock
|-
| R601 || Pulse amplifier
|-
| R602 || Pulse amplifier
|-
| R603 || Pulse amplifier
|-
| R650 || Bus driver
|-
|}

=== S series ===

The S series is identical to the R seriese except that its transistors switch faster and lower resistance resistors, allowing more cards to be wired in series and operate somewhat faster.

===W series===

The W stands for White. These are components that plug into Flip-Chip sockets, but have no logic of their own.

FLIP CHIP

2007-05-18T21:29:29Z

64.107.133.124: /* Flip-Chip families */

{{DEC-HW-stub}}
[[Image:B Series Flip Chip.jpg|thumb|300px|A B series Flip-Chip]]
'''Flip-Chip''' was a [[DEC]] registered trademark, named after the "flipchip" component mounting technique which quite rapidly faded from fame. The name was retained although the majority of Flip-Chips never really were flipchip-mounted as it became apparent that the flipchip mounting technique was highly unreliable. Flip-chips were used in the DEC [[PDP-7]] (Referred to in documentation as the "FLIP CHIP"), [[PDP-8]], [[PDP-9]] and [[PDP-10]], beginning on August 24, 1964.

In practice, they performed generic, simple functions, similar to an integrated circuit. They were approximately 4 inches long and 2.5 inches wide. Each had 36 connectors, 18 on each side.

== Naming ==

There appeared to be some confusion inside DEC at the time, as various manuals refer to it as "FLIP CHIP", "Flip Chip", "FLIP-CHIP", "Flip-Chip" and "Flip Chip", with trademark and registered trademark symbols.

==Flip-Chip families==

[[Image:FlipChips.jpeg|thumb|250px|Flip-chips in different forms and a rainbow of colors, in a [[PDP-8]].]]
The various families were colour-coded, and the first letter denoted a color, which was also visible on the handle.

===A series===

The A stands for Amber. The A series were used for analog functions - ADCs, DACs, amplifiers etc.

{|class="wikitable"
|-
| Part Number|| Description
|-
| A123 || Positive logic multiplexer
|-
| A131 || unknown
|-
| A200 || Op. amp.
|-
| A206 || Op. amp.
|-
| A207 || Op. amp.
|-
| A214 || unknown
|-
| A215 || unknown
|-
| A404 || sampler???
|-
| A613 || 12 bit DAC converter
|-
| A615 || unknown
|-
| A618 || 10 bit DAC converter
|-
| A619 || 10 bit DAC converter
|-
| A620 || 10 bit DAC converter
|-
| A621 || 10 bit DAC converter
|-
| A702 || reference supply???
|-
| A704 || reference supply???
|-
| A811 || 10 bit ADC converter
|-
| A990 || amplifier
|-
| A992 || amplifier
|}

===B series===

The B stands for Blue. The B series were used as core logic in the higher-end CPUs.

===G series===

The G stands for Green. The G series were used for "anything with non-standard voltages", I think.

===M series===

The M stands for magenta. Part of this line is simple TTL-level logic, while later on, it became quite complex, see [[list of DEC part numbers]]. They replaced the R series which used discrete transistors with integrated circuits.

* Power supply: 5 V
* Operate at up to 6 MHz

===R series===

The R stands for Red. Slower logic than the B series, but cheaper. Used extensively in the I/O circuitry of computers.

* Slower logic than B series, cheaper
* Used in a variety of systems, e.g. [[PDP-8]]
* Power supply 10 and -15 volts
* Operational to 2 megahertz
* Signal level 0 volts, logic 0 and -3 volts, logic 1
* Typical price $20 to $30

{| class="wikitable"
|-
| Part Number|| Description
|-
| R001 || Diode network
|-
| R002 || Diode network
|-
| R107 || Inverter
|-
| R111 || Expandable NAND/NOR gate
|-
| R113 || NAND/NOR gate
|-
| R121 || NAND/NOR gate
|-
| R122 || NAND/NOR gate
|-
| R123 || Input bus
|-
| R131 || Exclusive OR
|-
| R141 || AND/NOR gate
|-
| R151 || Binary to octal decoder
|-
| R181 || DC carry chain
|-
| R200 || Flipflop
|-
| R201 || Flipflop
|-
| R202 || Dual flipflop
|-
| R203 || Triple flipflop
|-
| R204 || Quadruple flipflop
|-
| R205 || Dual flipflop
|-
| R302 || Dual delay multivibrator
|-
| R303 || Integrating one shot
|-
| R401 || Variable clock
|-
| R405 || Crystal clock
|-
| R601 || Pulse amplifier
|-
| R602 || Pulse amplifier
|-
| R603 || Pulse amplifier
|-
| R650 || Bus driver
|-
|}

=== S series ===

The S series is identical to the R seriese except that its transistors switch faster and lower resistance resistors, allowing more cards to be wired in series and operate somewhat faster.

===W series===

The W stands for White. These are components that plug into Flip-Chip sockets, but have no logic of their own.

Category:IBM Computers

2007-05-18T17:36:29Z

64.107.133.124: New page: Category:IBM PC

[[Category:IBM PC]]

FLIP CHIP

2007-05-18T17:29:02Z

64.107.133.124:

{{DEC-HW-stub}}
[[Image:B Series Flip Chip.jpg|thumb|300px|A B series Flip-Chip]]
'''Flip-Chip''' was a [[DEC]] registered trademark, named after the "flipchip" component mounting technique which quite rapidly faded from fame. The name was retained although the majority of Flip-Chips never really were flipchip-mounted as it became apparent that the flipchip mounting technique was highly unreliable. Flip-chips were used in the DEC [[PDP-7]] (Referred to in documentation as the "FLIP CHIP"), [[PDP-8]], [[PDP-9]] and [[PDP-10]], beginning on August 24, 1964.

In practice, they performed generic, simple functions, similar to an integrated circuit. They were approximately 4 inches long and 2.5 inches wide. Each had 36 connectors, 18 on each side.

== Naming ==

There appeared to be some confusion inside DEC at the time, as various manuals refer to it as "FLIP CHIP", "Flip Chip", "FLIP-CHIP", "Flip-Chip" and "Flip Chip", with trademark and registered trademark symbols.

==Flip-Chip families==

[[Image:FlipChips.jpeg|thumb|250px|Flip-chips in different forms and a rainbow of colours, in a [[PDP-8]].]]
The various families were colour-coded, and the first letter denoted a colour, which was also visible on the handle.

===A series===

The A stands for Amber. The A series were used for analog functions - ADCs, DACs, amplifiers etc.

{|class="wikitable"
|-
| Part Number|| Description
|-
| A123 || Positive logic multiplexer
|-
| A131 || unknown
|-
| A200 || Op. amp.
|-
| A206 || Op. amp.
|-
| A207 || Op. amp.
|-
| A214 || unknown
|-
| A215 || unknown
|-
| A404 || sampler???
|-
| A613 || 12 bit DAC converter
|-
| A615 || unknown
|-
| A618 || 10 bit DAC converter
|-
| A619 || 10 bit DAC converter
|-
| A620 || 10 bit DAC converter
|-
| A621 || 10 bit DAC converter
|-
| A702 || reference supply???
|-
| A704 || reference supply???
|-
| A811 || 10 bit ADC converter
|-
| A990 || amplifier
|-
| A992 || amplifier
|}

===B series===

The B stands for Blue. The B series were used as core logic in the higher-end CPUs.

===G series===

The G stands for Green. The G series were used for "anything with non-standard voltages", I think.

===M series===

The M stands for magenta. Part of this line is simple TTL-level logic, while later on, it became quite complex, see [[list of DEC part numbers]]. They replaced the R series which used discrete transistors with integrated circuits.

* Power supply: 5 V
* Operate at up to 6 MHz

===R series===

The R stands for Red. Slower logic than the B series, but cheaper. Used extensively in the I/O circuitry of computers.

* Slower logic than B series, cheaper
* Used in a variety of systems, e.g. [[PDP-8]]
* Power supply 10 and -15 volts
* Operational to 2 megahertz
* Signal level 0 volts, logic 0 and -3 volts, logic 1
* Typical price $20 to $30

=== S series ===

The S series is identical to the R seriese except that its transistors switch faster and lower resistance resistors, allowing more cards to be wired in series and operate somewhat faster.

===W series===

The W stands for White. These are components that plug into Flip-Chip sockets, but have no logic of their own.

PDP-11/40

2007-05-16T17:41:59Z

64.107.133.124:

The PDP-11/40, introduced in 1973, was the first machine to introduce 18-bit memory addressing on the PDP-11 platform.

The OEM version of the 11/40 is the 11/35.

{{Infobox Machine
| name=PDP-11/40
| image=Pdp-11-40.jpg
| caption=PDP-11/40 with [[TU56]] dual [[DECtape]] drive.
| manufacturer=[[Digital Equipment Corporation]]
| word size= 16 bit
| virtual address= 16 bit
| physical address= 18 bit
| bus arch= [[UNIBUS]]|
|}}

{{stub}}

{{Template:PDP-11}}
[[Category:DEC processors]][[Category:UNIBUS processors]]

PDP-11/35

2007-05-16T17:41:23Z

64.107.133.124: Redirecting to PDP-11/40

#REDIRECT [[PDP-11/40]]

1977

2007-05-16T01:07:11Z

64.107.133.124: New page: {{stub}} =The year 1977 in computer history= {{year|year=1977|prev=1976|next=1978}} * The PDP-11/34a is introduced. * The PDP-11/60 is introduced * The VAX-11/780 is...

{{stub}}
=The year 1977 in computer history=
{{year|year=1977|prev=1976|next=1978}}

* The [[PDP-11/34|PDP-11/34a]] is introduced.
* The [[PDP-11/60]] is introduced
* The [[VAX-11/780]] is introduced.
* [[VAX/VMS]] 1.0 is introduced.

1978

2007-05-16T01:04:59Z

64.107.133.124: New page: {{stub}} =The year 1978 in computer history= {{year|year=1978|prev=1977|next=1979}} * The PDP-11/34c is introduced. * The VT100 terminal is introduced. * The [[DECwriter...

{{stub}}
=The year 1978 in computer history=
{{year|year=1978|prev=1977|next=1979}}

* The [[PDP-11/34|PDP-11/34c]] is introduced.
* The [[VT100]] terminal is introduced.
* The [[DECwriter III]] is introduced.
* The [[TU78]] is introduced.
* The [[RL02]] is introduced.

RSX-11

2007-05-15T19:09:23Z

64.107.133.124:

{{wp-orig}}

'''RSX-11''' is a family of [[real-time operating system]]s mainly for [[PDP-11]] computers created by [[Digital Equipment Corporation]] (DEC), common in the late [[1970s]] and early [[1980s]]. It was designed for and much used in process control, but was also popular for program development.

[[Dave Cutler]] was the project leader for RSX-11M, which was an adaptation of the earlier RSX-11D for a smaller memory footprint. Principles first tried in RSX-11M later appeared in DEC's [[Virtual Memory System|VMS]]. Microsoft's [[Windows NT]] system is a distant descendant of RSX-11M but is more directly descended from an object-oriented operating system Cutler developed for a RISC processor ([[DEC PRISM|PRISM]]) which was never released. This lineage is made clear in Cutler's foreword to <cite>Inside Windows NT</cite>, quoted on Neil Rieck's [http://www3.sympatico.ca/n.rieck/docs/Windows-NT_is_VMS_re-implemented.html "Windows-NT" is "VMS re-implemented"] page.

==Versions==
RSX-11 existed in many versions:
*RSX-11A, C -- small paper tape real time executives.
*RSX-11B -- small real time executive based on RSX-11C with support for disk I/O. To start up the system, first DOS-11 was booted, and then RSX-11B was started. RSX-11B programs used DOS-11 macros to perform disk I/O.
*RSX-11D -- a multiuser disk-based system. Evolved into IAS.
*IAS -- a timesharing-oriented variant of RSX-11D released at about the same time as the PDP-11/70. The first version of RSX to include DCL ([[Digital Command Language]]), which was originally known as PDS (Program Development System). This eventually superseded MCR as the default CLI in RSX-11M (Possibly by -11M v4.4?).
*RSX-11M -- a multiuser version that was popular on all PDP-11s.
*RSX-11S -- a memory-resident version of RSX-11M used in embedded real-time applications.
*RSX-11M-Plus -- a much extended version of RSX-11M, originally designed to support the [http://groups.google.com.au/groups?selm=7656%40shlump.nac.dec.com&rnum=2 multi-processor PDP-11/74], a computer that was never released, but also used widely as a standard operating system on the PDP-11/70.
*RSX-20F --11/40 front end processsor operating system for the DEC KL10 processor. Derived from RSX-11S
*Micro/RSX -- a stripped-down version of RSX-11M-Plus implemented specifically for the Micro/PDP-11, a low-cost multi-user system in a box, featuring ease of installation, no system generation, and a special documentation set.
*P/OS -- A version of RSX-11M-Plus that was targeted to DEC's PRO-325, [[PRO-350]], and PRO-380 line of [[PDP-11]]-based [[personal computers]].
*DOS/RV, OSRV-SM -- Two names for the clandestine clone of RSX-11M that was produced in the Socialist bloc. This system appeared to be an exact duplicate of RSX-11M save that the prompt was changed in the binary files. According to other sources, RSX-11M source code might have been stolen by the KGB. If read as Cyrillic, the name OSRV is an abbreviation for 'Operatsionnaya Sistema Realnogo(Razdelenija) Vremeni' -- Russian for 'Real Time(Time dividing) Operating System'. Not surprisingly, the six-character string 'OSRVSM' fits nicely in the same 16-bit [[RADIX-50]] word as 'RSX11M'. But, there are differences between RSX and OSRV because of differences between SM and PDP' hardware and recognised by Soviet engineers bugs in RSX. (OSRVM is the next model of OSRV-SM for the SM-1425.[http://web.archive.org/web/20050119123952/http://www.computer-museum.ru/histussr/sm1425.htm]) But RSX11M 'patched' for the SM's processor was used more often than rewritten OSRV. That happened because of better work by the RSX-11' re-coders, stability of patched RSX, and a faster update cycle for SM-RSX drivers & patches, made possible by the SM users community. OSRV and RSX driver interfaces are different & incompatible.

==Quotes==
*"RSX was a separate path at DEC and the progenitor more than anything of VMS that went to NT via Dave Cutler." -- [[Gordon Bell]], Vice President, Research and Development, Digital Equipment Corporation.

*"My first operating system project was to build a real-time system called RSX-11M that ran on Digital's PDP-11 16-bit series of minicomputers. ... a multitasking operating system that would run in 32 KB of memory with a hierarchical file system, application swapping, real-time scheduling, and a set of development utilities. The operating system and utilities were to run on the entire line of PDP-11 platforms, from the very small systems up through the PDP-11/70 which had memory-mapping hardware and supported up to 4 MB of memory." -- Dave Cutler, [http://www3.sympatico.ca/n.rieck/docs/Windows-NT_is_VMS_re-implemented.html foreword] to <cite>Inside Windows NT</cite>

==RSX-11 trivia==
*In order to support large programs within the PDP-11's relatively small [[virtual address]] space of 64 [[kilobyte|KB]], a sophisticated semi-automatic overlay system was used; for any given program, this overlay scheme was produced by RSX's ''taskbuilder'' program (called ''TKB''). If the overlay scheme was especially complex, taskbuilding could take a rather long time. Outside the office of the engineer in charge of ongoing maintenance of the taskbuilder was a [[whiteboard]] labeled "Taskbuilder wishlist". For several years, the top item on the wishlist was "same day service".
*Before DCL, the usual RSX prompt was ">" or "MCR>", standing for the "Monitor Console Routine".
*When run on certain PDP-11 processors, each version of RSX displayed a characteristic light pattern on the front of the processor any time the system was idle (and the processor was executing the PDP-11 ''WAIT'' instruction). The RSX-11M light pattern was two sets of lights that swept outwards to the left and right from the center of the light display (or inwards if the IND indirect command file processor program was currently running). The IAS light pattern was a single bar of lights that swept leftwards. 

==See also==
* [[QIO]]
* [[Asynchronous System Trap|AST]]
* [[Event flag]]
* [[RSTS/E]]
* [[RT-11]]

==External links==

*Dan Brevik posted a [http://groups.google.com/groups?selm=g11Va.162679%24ye4.109589%40sccrnsc01&output=gplain history of precursors to RSX-11] in [http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&safe=off&group=alt.sys.pdp11 alt.sys.pdp11].

*[http://web.archive.org/web/20050404121912/http://www.demillar.com/RSX/ Dan's RSX-11 prehistory] contain documents which trace RSX-11 back through RSX-15 and the real time executive written by John Neblett in the late 50's for the RW-300 process control computer. (Via archive.org, version fetched April 4, 2005)

*[http://www.spies.com/~aek/ Al Kossow] posted some further [http://groups.google.com/groups?dq=&hl=en&lr=&ie=UTF-8&safe=off&selm=bij4na%24r8v%241%40spies.com notes on RSX-11] in [http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&safe=off&group=alt.sys.pdp11 alt.sys.pdp11].

[[Category:Operating Systems]]
[[Category:DEC Operating Systems]]
[[Category:PDP-11 Operating Systems]]
[[Category:PDP-11 Software]]
[[Category:Real-time operating systems]]

DECnet

2007-05-15T00:49:44Z

64.107.133.124: /* Brief overview of the evolution of DECnet */

{{wp-orig}}
'''DECnet''' is a proprietary suite of network protocols created by [[DEC]], originally released in [[1975]] in order to connect two [[PDP-11]] [[minicomputers]]. It evolved into one of the first peer-to-peer network architectures, thus transforming DEC into a networking powerhouse in the [[1980s]].

Initially built with four layers, it later ([[1992]]) evolved into a seven layer [[Open Systems Interconnection|OSI]] compliant networking protocol, around the time when open systems ([[POSIX]] compliant, i.e. [[Unix-like]]) were grabbing marketshare from the proprietary OSes like VAX/VMS and AlphaVMS.

DECnet was built right into the DEC flagship operating system [[OpenVMS|VAX/VMS]] since its inception.
Digital ported it to its own [[Ultrix]] variant of [[Unix|UNIX]], as well as [[Apple Macintosh]] computers and PCs running both DOS and Windows under the name '''DEC Pathworks''', transforming these systems into DECnet end-nodes in a network of [[VAX]] machines. More recently, an open-source version has been developed for the [[Linux]] OS: see [http://linux-decnet.sourceforge.net/ Linux-DECnet on Sourceforge].

==Brief overview of the evolution of DECnet==

DECnet refers to a specific set of hardware and software networking products which implement the '''DIGITAL Network Architecture''' (DNA). The DIGITAL Network Architecture is essentially a set of documents which define the network architecture in general, state the specifications for each layer of the architecture, and describe the [[protocol stack|protocols]] which operate within each layer. Although [[packet sniffer|network protocol analyzer tools]] tend to categorize all protocols from DIGITAL as "DECnet", strictly speaking, non-routed DIGITAL protocols such as LAT, SCS, AMDS, LAST/LAD are not DECnet protocols and are not part of the DIGITAL Network Architecture.

To trace the evolution of DECnet is to trace the development of DNA. The beginnings of DNA were in the early 1970s. DIGITAL published its first DNA specification at about the same time that [[IBM]] announced its [[Systems Network Architecture]] (SNA). Since that time, development of DNA has evolved through the following phases:

'''Phase I''' ([[1974]])
Support limited to 2 [[PDP-11]]s running the [[RSX-11]] operating system only, with communication over point-to-point ([[DDCMP]]) links between nodes.

'''Phase II''' ([[1976]])
Support for networks of at least 100 nodes with multiple, different implementations which could interoperate with each other. Implementations expanded to included [[RSTS]], [[TOPS-10]] and [[TOPS-20]] with communications between processors still limited to point-to-point links only. Introduction of file transfer (FAL), remote file access (DAP), task-to-task programming interfaces and network management features.

'''Phase III''' ([[1980]]).
Support for networks of up to 255 nodes over point-to point and multi-drop links. Introduction of adaptive routing capability, downline loading (MOP), record access, a network management architecture, and gateways to other types of networks including IBM’s SNA and [[ITU-T|CCITT]] Recommendation [[X.25]].

<div style="float:right;margin:15px;margin-top:0px;padding:0px;border: 1px solid #aaa;">

{| border="0" cellspacing="2" cellpadding="2"
|+ '''DECnet Phase IV protocol suite'''
|----- align="left"
! Application
| DAP: Data Access Protocol<BR>
CTERM: Command Terminal
|----- align="left"
! Network Management
| NICE: Network Management protocol<br>
MOP: Maintenance Operation Protocol
|----- align="left"
! Session
| SCP: Session Control Protocol
|----- align="left"
! Transport
| NSP: Network Service Protocol
|----- align="left"
! Network
| DRP: DECnet Routing Protocol
|----- align="left"
! Data link
| DDCMP: Digital Data Communications Message Protocol<br>[[Ethernet]], [[IBM token ring|Token ring]], [[HDLC]], [[Fiber distributed data interface|FDDI]], ...
|----- align="left"
! Physical
| [[Ethernet]], [[IBM token ring|Token ring]], [[Fiber distributed data interface|FDDI]], ...
|}
</div>
'''Phase IV''' and '''Phase IV+''' ([[1982]]).
Phase IV was released initially to [[RSX-11]] and [[OpenVMS|VMS]] systems, later [[TOPS-20]], [[TOPS-10]], [[ULTRIX]], [[VAXELN]], and [[RSTS/E]] gained support. Support for networks of up to 64,449 nodes (63 areas of 1023 nodes), datalink capabilities expanded beyond DDCMP to include [[Ethernet]] [[local area network]] support as the datalink of choice, expanded adaptive routing capability to include hierarchical routing (areas, level 1 and level 2 routers), [[VMScluster]] support (cluster alias) and host services (CTERM). CTERM allowed a user on one computer to log into another computer remotely, performing the same function that [[Telnet]] does in the [[TCP/IP]] protocol stack. Digital also released a product called the PATHWORKS client, and more commonly known as the PATHWORKS 32 client, that implemented much of DECnet Phase IV for DOS, and 16 and 32 bit Microsoft Windows platforms (all the way through to Windows Server 2003).

Phase IV implemented an 8 layer architecture similar to the [[OSI model|OSI]] (7 layer) model especially at the lower levels ''(see diagram below)''. Since the OSI standards were not yet fully developed at the time, many of the Phase IV protocols remained proprietary.

The Ethernet implementation was unusual in that the software changed the physical address of the Ethernet interface on the network to AA-00-04-00-xx-yy where xx-yy reflected the DECnet network address of the host. This allowed router-less LAN operation because the LAN address could be deduced from the DECnet address. This precluded connecting two NICs from the same DECnet node onto the same LAN segment, however.

The initial implementations released were for [[Virtual Memory System|VMS]] and RSX-11, later this expanded to virtually every [[operating system]] DIGITAL ever shipped with the notable exception of [[RT-11]]. DECnet stacks are found on Linux, SunOS and other platforms, and Cisco and other network vendors offer products that can cooperate with and operate within DECnet networks. Full DECnet Phase IV specifications are available.

At the same time that DECnet Phase IV was released, the company also released a proprietary protocol called [[Local Area Transport|LAT]] for serial terminal access via [[Terminal server]]s. LAT is entirely separate from DECnet, though many DECserver LAT terminal servers did use MOP for the server image download and related bootstrap processing.

Enhancements made to DECnet Phase IV eventually became known as DECnet Phase IV+, although systems running this protocol remained completely interoperable with DECnet Phase IV systems.

'''Phase V''' and '''Phase V+''' ([[1987]]).
Support for very large (architecturally unlimited) networks, a new network management model, local or distributed name service, improved performance over Phase IV. Move from a proprietary network to an [[Open Systems Interconnection]] (OSI) by integration of ISO standards to provide multi-vendor connectivity and
compatibility with DNA Phase IV, the last two features resulted in a hybrid network architecture (DNA and OSI) with separate “towers” sharing an integrated transport layer. Transparent transport level links to [[TCP/IP]] were added via the [[Internet Engineering Task Force|IETF]] [[Request for Comments|RFC]] 1006 (OSI over IP) and RFC 1859 (NSP over IP) standards ''(see diagram below)''.

It was later renamed '''DECnet/OSI''' to emphasize its OSI interconnectibility, and subsequently '''DECnet-Plus''' as TCP/IP protocols were incorporated.

==References==

* [[Carl Malamud]], ''Analyzing DECnet/OSI Phase V''. Van Hostrand Reinhold, 1991. ISBN 0-442-00375-7.

* James Martin, Joe Leben, ''DECnet Phase V: An OSI Implementation''. Digital Press, 1992. ISBN 1-55580-769-0.

* DECnet-Plus manuals for OpenVMS are available at http://www.hp.com/go/openvms/doc/

* DECnet Phase IV OpenVMS manuals for DECnet Phase IV; these Phase IV manuals are archived on OpenVMS Freeware V5.0 distribution, at http://www.hp.com/go/openvms/freeware and other sites.

* DECnet Phase IV architecture manuals (including DDCMP, MOP, NICE, NSP, DAP, CTERM, routing); at http://ftp.digital.com/pub/DEC/DECnet/PhaseIV/ and other sites.

[[Category:Network protocols]]
[[Category:OpenVMS]]

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<big>'''Welcome to the computer history wiki!'''</big>

This wiki is an experiment by me to create a means for knowledgeable people to enter their information into some kind of a knowledge base, however, not including the relatively formal tone imposed by Wikipedia. For example, sentences with "I seem to recall" would be perfectly legitimate, and even wanted, here, but would quite rapidly be weeded out of a Wikipedia article.

My desire to set up this English wiki stems from my frustration with adding information to a Norwegian wiki, the Norwegian Computer History Society wiki, and realizing that my content would be reachable only to a very limited audience - Scandinavians, at best.

If you have any information you want to contribute to this wiki, '''please, do it'''. I'd much rather remove or modify ten or twenty bad submissions than miss out on a potentially good one.

I hope this wiki could grow into a useful resource at some point, for everyone interested in classic computing, on all points of the knowledge scale. I realize that there are more specific wikis for Commodore and Amiga and so on, but this is an effort to be a more general computing history wiki.

Though the current URL is of course temporary, this is an experiment to see if people actually make edits to this page and find it useful. If it "catches on", I will register a domain with an appropriate name. (My threshold for "catches on" is quite low.) Worst case scenario, this becomes a one-user CMS; I'd write this on my homepage if it wasn't in a Wiki. :)

[[User:Toresbe|Toresbe]] 16:53, 14 May 1818 (PDT)