Motorola 68K computer

Agfa ADC 5155 Motorola 68K Computer Teardown (Part 2 of 4)

This is the reverse engineering and teardown of a very interesting computer that runs on VME framework developed for the Motorola 68000 series CPUs. It runs a custom operating system called Monitor 4.28 developed by Agfa-Gevaert NV, Belgium.

I reverse engineered the operating system without any prior knowledge of how it worked. Throwing random commands at it I at some point discovered the “HE” command would show a full menu of commands that it would accept at the serial service port at the front of the computer.

List of commands:

  • ATX = Execute ASTRX shell command
  • BF = Block fill
  • BI = Block initialize
  • BM = Block move
  • BS = Block search
  • BT = Block test
  • BR = Breakpoints (BR -* clear)
  • BRS = Set Breakpoints cmd string
  • BO = Boot from disk
  • CPU = Set CPU parameters
  • CWS = Show Clock and Wait states
  • DA = Display or set DATE
  • DCP = Disk copy from 10 to 00
  • DI = Disassembler
  • DOS = Enter DOS mode
  • DU = Dump sector from disk
  • GO = Go target
  • GN = Go target, break at next instr
  • GT = Go target, set temporary break
  • HE = Help
  • fep = Show FEP info
  • IOP = IO disk read and write
  • IOT = IO teach
  • JSR = Jub to subroutine
  • LO = Load S-records
  • LOG = Show OS RAM logging
  • MAP = Select memory map
  • MD = Memory display
  • ML = Memory display link (range) == address1,address2 or address:count
  • MM = Memory modify
  • MS = Memory set
  • NAM = Show symbolic name
  • PF = Set Port format
  • PRJ = Select project
  • RAM = RAM test
  • RD = Register display
  • RDF = Display floating point regs
  • RDM = Display MMU regs
  • RES = Reset
  • SC = Set Control options
  • ST = Start clock
  • -swi = Switch CPU
  • T = Trace next (step into JSR)
  • TR = Trace next (skip over JSR)
  • TC = Trace on change of flow
  • TM = Transparent mode
  • TI = Display & Set clock time
  • TE = Switch to TEST menu
  • US = Start user program
  • VE = Verify S-records
  • VEC = Show vectors
  • VIC = Show VIC & hardware
  • VME = VME remote control
  • VIX = Boot from disk
  • X = Execute external shell command
  • XT = File transfer protocol

Mads Barnkob

Electrician, programmer, experimenter and amateur scientist with experience in industry automation, programming and all kinds of high voltage generating electronics. Administrator of www.kaizerpowerelectronics.dk and the high voltage community forum www.highvoltageforum.net

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