DZ11 asynchronous serial line interface

M7819 EIA DZ11 card

The DZ11 was a UNIBUS 8 port asynchronous serial line mux card for DEC computers. It used used programmed I/O, and thus could present a considerable load on the CPU when running a high speed line. A 64-entry FIFO buffer silo was provided on the input side.

Both EIA and 20mA physical layers were supported; the EIA model could operate with full-duplex modems. It provided program-set baud rates (up to 9600 baud), but not split speed. Break could be detected or generated on each line.

Implementation

Physically, it was a hex card, which plugged into an 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 PCB of that is 54-11928). The H317-E held 16 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

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

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 addresses 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)

TRDY	TIE	SA	SAE	Unused	Tx Line			RDONE	RIE	MSE	CLR	MAINT	Unused
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

• 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 UARTs
• MAINT - Maintenance loopback enabled

Receiver Buffer Register (RBUF)

DV	OVR	FRERR	PERR	Unused	Rx Line			RBUF
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

Line Parameter Register (LPR)

Unused			RXON	Speed				ODDP	PAREN	STOP	CLEN		Line
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

Transmit Control Register (TCR)

DTR								Line Enabled
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

Modem Status Register (MSR)

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

Transmit Data Register (TDR)

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

Further reading

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

External links

• DZ11 user's guide (EK-DZ110-UG-002)
• DZ11 asynchronous multiplexer technical manual (EK-DZ110-TM-002)
• DZ11-A,B,E (EIA) Field Maintenance Print Set (MP00132)