Commodore SuperPET

  • Posted by Mike Naberezny in Hardware

    I’ve been spending more of my free time recently restoring vintage computer hardware. I am interested in Commodore 8-bit equipment, from the PET/CBM line through to the 64/128 home computers. I think it’s important to preserve computer history to remember the machines that got us where we are today.

    Since much of the hardware I restore is over twenty-five years old, at least half of it is not working when I receive it. I try to repair everything I can when it’s practical. My Flickr photos page has daily progress of my chip-level repairs on this equipment.

    Recently, I received a Commodore SuperPET computer. This is a remarkable machine that was a collaboration between Commodore and the Computer Systems Group at the University of Waterloo in Ontario, Canada. The SuperPET is a standard Commodore PET 8032 computer with an internal expansion that adds a powerful Motorola 6809 microprocessor, an additional 64K of expansion RAM, a fast 6551-based RS232 serial port, and custom Waterloo software in ROM.

    The SuperPET can operate in MOS 6502 mode, where it is a Commodore PET 8032 with the extra 64K expansion and 6551 ACIA. Curiously, this 64K expansion memory is not compatible with the 8096. A switch on the side puts the SuperPET into 6809 mode, where it can run a number of disk-based Waterloo programming languages including BASIC, Pascal, APL, Fortan, and COBOL. When in 6809 mode, a menu in ROM prompts the user to select a language which is then loaded from disk.

    My SuperPET seemed to work when I got it, with the 6502 mode working perfectly and 6809 mode showing the power-on menu. However, after obtaining the disk-based software, none of the Waterloo languages would run after loading. After verifying the disks were good, I suspected the 64K expansion RAM since the rest of the machine seemed to be working. Using technical information from the PET Index on, I wrote several memory test programs to exercise the expansion RAM.

    The expansion RAM is comprised of thirty-two 4116 DRAM chips. A couple of these had become loose from their sockets and my test program found that one of them had failed. I got a replacement from the pick-up counter at Jameco and installed it. Now, my SuperPET passes my expansion memory test and also boots all of the Waterloo languages. It is now fully functional and I’m exploring the Waterloo software.

    One of the most interesting features of the Waterloo languages is how files are accessed. Commodore disk drives attached to the SuperPET are accessed with a filename like disk8/1.program-name which selects unit 8, drive 1. The SuperPET was designed to be attached to a mainframe computer, known as the “host”, through its serial port. Accessing a file like host/program-name would load it from the mainframe if it was running the special HOSTCM program from Waterloo.

    The HOSTCM program was available for VM/CMS and other mainframe operating systems. Beyond that, I’ve not been able to find out much information about it. I would like to figure out the protocol and write a program so that a modern PC could be used as a host computer for the SuperPET.

    If you have any information on the SuperPET or have Commodore hardware you’d like to donate, please contact me.


  • comment by Ian M 23 Feb 09

    Hi Mike,

    I must say, that your restoration work is certainly interesting and worth following.
    I have been taking a look through your website, in search of some help with Commodore 64 / Commodore PET / Commodore 128. I will be coming into a stock of them (2x 128, 1×64, 1x PET 4032).

    I haven’t used a Commodore system since I was a child, so I am a bit rusty with the systems, however I do want to get back into using them. I do actually have a plan on them, and I am wondering if I could bounce some ideas off of you.

    I will admit, I am not a basic programmer, so I am a bit lost with it. I am wondering what sort of Network functionality would be possible with a Commodore, I have done some digging and I can’t really find anything about it, I am wondering if it would be possible to set up a serial network / bbs functionality? At least with the C128s?

    I am assuming Ethernet is out of the question, what about token ring? I apologize for not being fully informed with the issue.

    If you could contact me back at that would be greatly appreciated, Thanks!

  • comment by Gary Ratliff Sr. 27 Jul 09

    I was an Associate Editor of the SuperPET Gazette for several years. I recently downloaded the manuals for all the SuperPET languages in pdf format. I think this was from Dav’s Old Computers. He has quite a collection of old computers and may be able to help with your restoration efforts.

    While working of the Gazette the editor sent me a disk with most of the software projects from its first two years of operation. This was in 1981 and once the IBM PC claimed to have invented computers and took over the market most of the users switched to either the Amiga or the to PC. I have long ago misplaced these disks. Good luck with your restoration and data gathering efforts.

    I still have a Kaypro 10 and a Zorba sustem which runs CP/M and has z80 chips. This ran the last time I took it out of storage.



    PS. I am currently writing a series of artciles on computer languages:
    An Alphabet of Computer Languages. I have has articles in issues since the Dec. 2007 issue and till the change of editors to the one who seemed to abandon the magazine.

  • comment by Reg Beck 1 Dec 09

    You are lucky to find one. I should have kept mine but had no room and needed a PC for a programming job I had so had to get rid of it. I bought mine and the dual floppy drive (and later the single high density floppy drive) soon after they came out. I wrote a script for my dot matrix printer that allowed it to print the APL character set. I came to the SuperPet via the Commodore 8K Pet and was already a BASIC programmer. I had taken a summer institute course in APL and also learned the 6809 Assembler and Pascal. A couple of years after I got the machine I became the APL column editor of the SuperPet user group’s publication, “The SuperPet Gazette”. It was an incredible machine and it wouldn’t have bothered me at all if the evolution of computing machines had ended with the SuperPet! By the time the user group folded we had completely figured out how the SuperPet worked. Unfortunately, the editor of the user group moved on to an Amiga and soon after that followed the demise of the SuperPet.

  • comment by mark 9 Sep 10

    Hello gentlemen.

    I have a few PETS that Ive had in storage for awhile.. and im starting to bring them out. My SuperPet was taking like 20-25 flicks of the power switch to get it to boot. then would last a little while and lock up. Any pointers ? now it doesnt seem to wanna turn on at all. I have other machines im going to start to get alive and tinker with. any advice ?

  • comment by Jeff 11 Sep 10

    It’s surprising how often RAM is the problem with these aging machines. Re-seating the chips in the sockets is sometimes all it takes, but I had a C64 in which one of the 4164 chips actually went bad .. and the 4164s in the C64 were not socketed, so this involved solder.

  • comment by John Seither 20 Oct 13

    I bought my SuperPET new in about 1983 while stationed in Hawaii with NCIS. I still have it and the 8250 quad density drive in their original boxes. Neither have been used since at least the early 90s, at which time they were functioning. My wife and I very much enjoyed the SuperPET Gazette, which we subscribed to for at least a couple of years. I always wondered what happened to the editor – nice fellow as I remember. We sent him a plastic template I had made with a mid-1980s plotter.

  • comment by Michael Szeller 2 Oct 14

    I was involved as a Student at Brandon University when they purchased about 30 of these to extend the student programming facilities. At the time system programming languages were all done on the University’s VAX 11/750 mini computer and it was getting pretty overloaded as the number of students entering CompSci skyrocketed. We undertook a project to write a version of HOSTCM to run on the VAX. We also added a VT-52 emulation in ROM so the SuperPET could either download the Waterloo Languages from the VAX (and save work back) or use the VT-52 emulation to access the VAX to do programming on it. All in all it was a pretty cool machine for it’s day. At the time I personally was running a Commodore 64, so I could appreciate the differences between the two platforms.

  • comment by Norman Davie 21 Feb 15

    I took my first programming course with the Commodore SuperPET in 1979- IN APL! I was wondering if you have any video of the machine in operation.
    I noticed there is *nothing* on youtube demoing this great piece of history.

  • comment by David Bradley 12 Apr 15

    I am in the process of going through my Commodore collection and it seems I have three SuperPET’s…I am just about to start going through them…just wondering where it is that you got the disks for the 6809 side of things?


  • comment by John Bossom 5 Dec 15

    If you have the SuperPET 6809 Assembler manual… you will find me on the acknowledgement page… I wrote the bank-switched 6809 linker for it while on work-term at the Computer Systems Group at the University of Waterloo (nostalgia)

  • comment by James Little 14 Jul 16

    I learned to program in Pascal on a SuperPet in HighSchool in 1987. Good times.

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