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Commodore MMF 9000 (SuperPET 9000) Repair & Testing

Commodore MMF 9000 (SuperPET 9000)

The SuperPET is a Commodore PET 8032 with one or two added boards that were designed at the University of Waterloo.

The computer has a built-in RS-232C interface and many programming languages on Floppy Disk. In Europe, this machine was called the MicroMainFrame 9000, or MMF 9000.

Let’s start to assembling the BMB Compuscience Ltd Board and Compu-Think 64K Memory Expansion board in the Commodore MMF 9000 (SuperPET)

I had to shorten the original standoffs installed in the computer because the length was wrong for the two boards BMB Compuscience/Compu-Think 64K. The long standoffs are used for the superPET Combo Board (the last one released).

It was not a simple job, obviously i have looked around for the identical standoffs with thickness, size, pitch and some with a long screw other with a short screw.

Between one phase and another i have also giving a nice clean inside and outside of the computer and of the motherboard.

Unfortunately there are a couple of problems after assembling the two boards of the MMF 9000 (SuperPET).


  • The keyboard space bar dead.
  • Don’t runs any Waterloo program in the 6809 environment, runs only the Bootstrap menu which allows to load the programs from Floppy Disk, the Machine Language monitor and the Setup program both are in the Eprom.
  • The protection Dongle (6702) not correctly viewed from the system.


  • The keyboard after a good cleaning has started to work well.
  • The Dongle after cleaning the contacts now works.

About the programs that don’t runs in the 6809 environment the repair was a bit longer. I have used the only program that worked under the 6809 environment, the Machine Language Monitor.

With this program i have filled the memory with the command Fill (f 9000-9fff aa) and i have changed from time to time the bytes that i was going to write in memory and  i have used the command (d 9000-) to see the results and not all memory locations are written correctly.

With the Bank Switching command (b 0, b 1 …) i have switch the memory bank, there are 16 banks of 4k each for a total of 64k.

I have found 7 x 4116 RAM failed (this card is new, never used), replaced these bad RAMs everything has started to work properly.

So my advice is to try to load the Waterloo software in the 6809 environment to make sure that the 64k memory expansion (only seen in the 6809 environment) is working properly.

Below the photos of all the tests that i have done:

  • Test with the CPU 6502 (Standard Commodore 8032/32k) with disk access, some software running in emulation 40 columns with the program: 80240.prg
  • Test with the CPU 6809 of the entire Waterloo software package with disk access.


This is a archive with documents, disk images and rom files usefully to test the computer.

Download: MMF9000/SuperPET Documents,Disk images,ROM Files (345)

  1. Andy
    March 11th, 2018 at 15:06 | #1

    Did you experience any screen wobble (50hz ripple) when in 6809 mode ?

    I have a SuperPet configured for 60Hz (am based in Europe) and wondered if the ROMS on the 6809 board are different for EU frequency…