View source for DS11 Multiple Line Synchronous Interface

The '''DS11 Multiple Line Synchronous Interface''' was an early [[synchronous serial line]] [[peripheral|interface]] for the [[UNIBUS]]; it could handle up to 16 lines. It used [[programmed I/O]] (with separate receive and transmit [[interrupt]]s) to transfer data; it could operate in either [[half-duplex]] or [[full-duplex]] mode. 

Character lengths of 6, 8 and 12 bits were supported, and could be configured by software. It provided an [[EIA RS-232 serial line interface|EIA RS-232]] interface to Bell 200 series [[modem]]s (such as the model 201, and equivalents), and also connect to Bell 300 series modems, such as the model 303.

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optionally a [[20mA current loop serial line interface|current loop]] interface (to Bell 300 series modems, such as the model 303, and equivalents). [[Baud rate]]s of up to 9.6K bits/second were supported by the EIA interface, and up to 100K bits/second by the current loop interface.

The [[character]] length (5, 6, 7 or 8 [[bit]]s), and the [[sync character]], were selectable; [[parity]] (even or odd) was optionally supported for error detection. All configuration, as well as all the modem control leads, could be set under program control. A [[jumper]] allows configuration of whether one or two contiguous sync characters is needed for synchronization.

It apparently supported idling (sending the sync character); the line could also be set to a [[serial line|mark]] condition when not transmitting characters.
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==Registers==

{| border=1
! Register !! Abbreviation !! Address
|-
|Receiver Status Register                  || RxCSR || 775xx0
|-
|Receiver Data Buffer Register             || RxDBUF || 775xx2
|-
|Transmitter Status Register               || TxCSR || 775xx4
|-
|Transmitter Data Buffer Register          || TxDBUF || 775xx6
|-
|Interface Status Register                 || ISTR || 775600
|}

Line addresses:

* Line 0: 775400-775406
: ...
* Line 15: 775570-775576

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'''.

===175xx0: Receiver Status Register (RxCSR)===

{{16bit-header}}
| RING || BITOVR || CHAROVR || CARLST || colspan=2 | SYNCST || ''CARDET'' || DTR || ''DONE'' || ''DSR'' || colspan=2 | CHARLEN || colspan=2 | DNIA || RNGENB || RCVENB
{{16bitoctal-bitout}}

* BITOVR - Bit Overrun
* CHAROVR - Character Overrun
* CARLST - Carrier Lost
* SYNCST - Sync State
* CARDET - Carrier Detected
* DTR - Data Terminal Ready
* DSR - Data Set Ready
* CHARLEN - Character Length
* DNIA - Done Interrupt Assignment
* RNGENB - Ring Enable
* RCVENB - Receiver Enable

===175xx2 (read): Receiver Data Buffer Register (RxDBUF)===

{{16bit-header}}
| colspan=4 | Unused || colspan=12 | RDBUF
{{16bitoctal-bitout}}

* RDBUF - Receiver Data Buffer

===175xx4: Transmitter Status Register (TxCSR)===

{{16bit-header}}
| Unused || BITOVR || CHAROVR || CTSLST || colspan=2 | Unused || ''CTS'' || DTR || DONE || ''DSR'' || colspan=2 | CHARLEN || colspan=2 | DNIA || IDLE || RTS
{{16bitoctal-bitout}}

* BITOVR - Bit Overrun
* CHAROVR - Character Overrun
* CTSLST - Clear to Send Lost
* CTS - Clear to Send
* DTR - Data Terminal Ready
* DSR - Data Set Ready
* CHARLEN - Character Length
* DNIA - Done Interrupt Assignment
* RTS - Request to Send

===175xx6: Transmitter Data Buffer Register (TxDBUF)===

{{16bit-header}}
| colspan=4 | Unused || colspan=12 | TDBUF
{{16bitoctal-bitout}}

* TDBUF - Transmitter Data Buffer

===175600: Interface Status Register (ISTR)===

{{16bit-header}}
| ''A3IN'' || ''A2IN'' || ''A1IN'' || colspan=3 | Unused || colspan=2 | VAHBITS || DIAGM || PRCLK || Unused || '''CLRBC''' || colspan=4 | ''DIAGBC''
{{16bitoctal-bitout}}

* A3IN - Adapter 3 In
* A2IN - Adapter 2 In
* A1IN - Adapter 1 In
* VAHBITS - Vector Address High Bits
* DIAGM - Diagnostic Mode
* PRCLK - Program Clock
* CLRBC - Clear Bit Counter
* DIAGBC - Diagnostic Bit Counter

==Interrupt vectors==

The DS11 uses an [[array]] of [[interrupt vector]]s, as follows:
{{16bit-header}}
| colspan=6 | Unused || colspan=2 | VAHBITS || colspan=4 | LINE || TINT || STINT || colspan=2 | 0
{{16bitoctal-bitout}}

* VAHBITS - Vector Address High Bits
* LINE - Line Number
* TINT - Transmitter Interrupt
* STINT - Status Interrupt

==Implementation==

The DS11 consisted of a master line scanner, and up to four adapters, each of which could handle up to four lines; each line had a separate [[DEC card form factor|quad]] M7110 Line Control Module. Physically, it is a large quad-height [[backplane]], mounted in a 19" cabinet such as an [[H960 rack|H950]], along with the DS11's [[DEC indicator panel]].

The DS11, like some other early UNIBUS peripherals, was made of many small [[FLIP CHIP]]s. The inventory of the card types in the DS11 is:

* G830 5V, 10A Regulator from 8V
* M002 Resistor network
* M126 6 x AND-NOR Gates
* M128 4,4 AND-NOR Gates
* M139 3 x 8-Input NAND Gates
* M143 10 x 2-Input NAND Gates
* M145 7 x 3-Input NAND Gates
* M147 5 x 4-Input, 1 x 2-Input NAND Gates
* M152 Dual Non-inverting Binary to Octal with Enable
* M165 Memory buffer, Inverting and Non-inverting Output
* M171 2-2-2-3 AND-NOR
* M173 10 x 2-input AND gates
* M174 4 En x 9 out mixer
* M175 7 x 3-input AND gates
* M177 5 x 4-Input AND Gates
* M178 8 En x 6 out mixer
* M181 Non-inverting 2-2-2-3 AND-NOR
* M211 6-Bit Up/Down Counter
* M241 6 x D Flip-flops with common clock
* M243 8 x D Flip-flops with 2 common clocks
* M246 5 x D Flip-Flops
* M253 16 Word, 12-bit Memory
* M307 Integrating One Shot
* M321 Tapped Delay Line
* M362 Delay, 25 to 50 ns
* M401 Variable Clock
* M603 Pulse Amplifiers
* M612 6 Power Gates
* M783 UNIBUS Drivers
* M784 UNIBUS Receiver
* M785 UNIBUS Transceiver
* M931 15 Terminators
* M969 24 Level Terminators
* M511 UNIBUS Receivers - sources differ as to whether or not this is used
* W990 Connectors
* [[M105 Address Selector]] - used to set its bus address
* [[M782 Interrupt Control|M7820 Interrupt Control]]
* M7110 Line Control Module - one per line

The number of each type used is currently unknown; likewise the locations in the backplane (except the M7110's)

{{semi-stub}}

==See also==

* [[DU11 synchronous serial line interface]]

==Further reading==

* ''DS11 Multiple Line Synchronous Interface Maintenance Manual'' (DEC-00-DS11-DB; not available online, but in fiche)

==External links==

* [http://bitsavers.org/www.computer.museum.uq.edu.au/pdf/DEC-10-XSRMA-A-D%20DECsystem10%20System%20Reference%20Manual.pdf DECsystem-10 System Reference Manual] - documents the DS11 registers in Appendix C (pp. 370-371 of the PDF)
* [http://www.bitsavers.org/pdf/dec/modules/mSeries/M7110.pdf M7110]
<!-- * [http://www.bitsavers.org/pdf/dec/modules/mSeries/M511.pdf M511] -->

[[Category: UNIBUS Synchronous Serial Interfaces]]