DS11 Multiple Line Synchronous Interface

The DS11 Multiple Line Synchronous Interface was an early synchronous serial line interface for the UNIBUS; it could handle up to 16 lines. It used programmed I/O (with separate receive and transmit interrupts) 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 interface to Bell 200 series modems (such as the model 201, and equivalents), and also connect to Bell 300 series modems, such as the model 303.

Registers

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)

RING	BITOVR	CHAROVR	CARLST	SYNCST		CARDET	DTR	DONE	DSR	CHARLEN		DNIA		RNGENB	RCVENB
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

• 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)

Unused				RDBUF
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

• RDBUF - Receiver Data Buffer

175xx4: Transmitter Status Register (TxCSR)

Unused	BITOVR	CHAROVR	CTSLST	Unused		CTS	DTR	DONE	DSR	CHARLEN		DNIA		IDLE	RTS
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

• 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)

Unused				TDBUF
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

• TDBUF - Transmitter Data Buffer

175600: Interface Status Register (ISTR)

A3IN	A2IN	A1IN	Unused			VAHBITS		DIAGM	PRCLK	Unused	CLRBC	DIAGBC
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

• 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 vectors, as follows:

Unused						VAHBITS		LINE				TINT	STINT	0
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

• 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 quad M7110 Line Control Module. Physically, it is a large quad-height backplane, mounted in a 19" cabinet such as an H950, along with the DS11's DEC indicator panel.

The DS11, like some other early UNIBUS peripherals, was made of many small FLIP CHIPs. 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
• 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)

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

• DECsystem-10 System Reference Manual - documents the DS11 registers in Appendix C (pp. 370-371 of the PDF)
• M7110