The Digital Minc-11

This describes the Minc-11

MINC-11 set
A MINC-11 set in a typical Dec laboratory setting

The MINC-11 system is basically a PDP-11/03 (later 11/23) but designed for laboratory use, as a succesor of the LINC system. It used a special set of interface modules and double spaced quad sized slots. The operating system is a special version if RT-11 which launces direct into MINC-Basic. Special functions address the MINC modules and graphic capabilities of the VT-105 terminal. The modules are:

Connecting the modules to the real world was sometimes done with BNC-connectors at the module front, but mainly via the connector block on top of the modules. The C/D connectors of the QBus are used to connect modules, like a preamplifier and/or multiplexer as A/D converter front end.

MINC Basic also supported instrument interfacing via serial and IEEE bus, but used conventional QBus cards for this (DLV11-J resp. IBV11)

This are the boards in my Minc-11, with info from the various DEC documents, I think useful and/or interesting.
KDF11-AA / M8186 microprocessor This board has the F-11 chipset:
  • Upper 40 pin chip: Basic processor Data unit DC302F, Control unit DC303D
  • Second 40 pin chip: Floating-point processor; Two control units DC303D
  • Third 40 pin chip: spare socket
  • Bottom 40 pin chip: MMU unit; DC304E

Found the I/O page at 770000 - 777777, so this is an 18-bit machine. Note this is in ODT mode, it is 177000 - 177777 when a program is executed. So ODT bypasses the MMU.

M8044 DH
MSV11-DD / M8044 DH 32 kW RAM 32 kW with Nec UPD416. The -5V required by the RAM chips is generated on board. Dynamic RAM refresh is also local. There is no parity bit on this board (MSV11-E only).
M8044 DB
MSV11-DD / M8044 DB RAM 32 kW with Mostek MK4116. The -5V required by the RAM chips is generated on board. Dynamic RAM refresh is also local. There is no parity bit on this board (MSV11-E only).
RX02 / M8029 floppy interface RX02 floppy interface. These are the commands
  • Fill Buffer,
  • Empty Buffer,
  • Write Sector,
  • Read Sector,
  • Set Media Density,
  • Maintenance Read Status,
  • Write Sector With Deleted Data,
  • Read Error Code.

Like with the RX01 interface, there is no way to format a floppy disk. As the format is unique for DEC, the only way to get an usable floppy is buying them from DEC. But it is possible to 'convert' a RX01 (standard IBM single density) to RX02. (RX02 is a single density sector header combined with double density data)

Booting from an RX01 or RX02 floppy means the bootstrap loader program has to be loaded first from the REV11-A or BVD11 option.

IBV11-A / M7954 IEEE-488 interface IEEE-488 interface. The IEEE-488 bus is widely used in laboratory environments, so this interface is very useful for a Minc.
The LSI11 GRANT CONTINUITY shorts AM2(BIAKI) with AN2(BIAKO), and AR2(BDMGI) with AS2(BDMGO). This configuration is not unique to the LSI11 GRANT CONTINUITY, all cards that do not use DMA or interrupts have these shorts.
BIAKI = Interrupt acknowledge input, BIAKO = Interrupt acknowledge output. BDMGI = DMA Grant Input, BDMGO = DMA Grant Output.
These connection allows unused slots between the processor and DMA and interrupt cards. Without this board, the DMA and interrupt chain would not work.
DLV11-J / M8043 four-channel asynchronous serial interface The four-channel serial interface. The 10 pin header on the board is connected to 9-pin DE-9 male connectors on the chassis. This ASCII art shows the connection and a cable to a standard PC serial port.

     DLV11-J 10 pin header    chassis 9-pin DE-9     EIA RS-232C DB-25 (25p.) female [DE-9 (9p.)]
      1 - 16x Baud rate -------- 1 --:-
      2 - GND ------------------ 3 --:- )----------------------( GND 7       [5]
      3 - XMIT DATA + ---------- 4 --:- )----------------------( RCV DATA 3  [2]
      4 - XMIT DATA - ---------- 5 --:-
      5 - GND ------------------ 9 --:-
      6 - slot
      8 - RCV DATA + ----------- 7 --:- )----------------------( XMIT DATA 2 [3]
      7 - RCV DATA - ----------- 8 --:- )--+
      9 - GND ------------------ 6 --:- )--+
     10 - +12V ----------------- 2 --:- 
For a real PC DB-25 also connect pin 4 with 5, and 6 with 8 and 20. For 9-pin DE-9: 7 with 8, and 1 with 4 and 6
BVD11 / M8012
  terminator, boot rom and control panel The LEDs on the board might be useful during startup when there is no prompt or other feedback, but as they are operated by software only, nothing happens in the critical phase. Most useful is the green LED indicating the bus voltages ar more or less ok.

S1 (Halt/Normal switch) / = processor in run mode; \ = processor in halt mode; (single instruction)

S2 (Boot/Normal switch) toggle is restart

There are lots of sockets and switches on the board, so how does it work?

  • E36, E40, E52 and E57 are hardwired for 2708 EPROM only (-5V on pin 21 and +12V on pin 19)
  • E44, E48, E53 and E58 are hardwired for 8316E masked boot/diagnostic ROM
  • All the other sockets can be configured for the 2708, 8316E or 2716 EPROM
MNCAD Analog-digital converter module
MNCAA Digital-analog converter module
MNCD0 Digital out module
MNCKW Clock module
Module order AD analog-digital module AA digital-analog module DO digital out module KW clock module The diagrams on top of the modules indicate that the MNCAD depends on a MNCKW in the slot right of it. One or more digital options in between are allowed as these pass the clock through the clock signals. If you want another analog-digital module, you also need a second clock module.

The MP01074_MDL-23_MINC_Engineering_Drawings_Jun80.pdf document at contains much info on the Minc-23 system.

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Last update: 2021-01-09