DZ11 asynchronous serial line interface

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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 User Guide, EK-DZ11-UG-002
  • DZ11 Maintenance Manual, EK-DZ11-MM-001