MC's Journal

Running CP/M: Microbee, Compis, and Yaze-AG

A couple of days ago I talked with a friend about computers in our primary schools. At her school they had a set of Microbee computers, a family of Australian Z80-based micros running CP/M. I don't know exactly what model they had, but after asking around among other friends some sort of Microbees seems to have been rather common in Swedish school in the mid-80s.

I remember seeing ads for Microbees in the 1980s and much later had an opportunity to play with a 32IC for a while. Quite nice little machines.

From 1985/86 my school had Compis computers, which I think was slightly more common, Compis being The Official Swedish School Computer. Compis was a 80186-based CP/M-86 machine with really nice, low keyboard and fairly high resolution monitors.

The system at my school were 640x400 monochrome (green) and a single colour-based machine with much slower graphics that everyone avoided. Allegedly there was also a version with 1280x800 monochrome (b/w), but I never saw anything like that.

The machines had floppy drives but were also connected to a shared 10 MiB hard disk. The hard-drive was only available in read-only form, except for one drive letter which only could have one user at a time. I remember a program called boxloss which unmounted this virtual drive from anyone who happened to be using it and mounting it for you. The password was “Fredrika”. I don't remember how you were supposed to mount it without stealing it like this. Anyone?

There was some kind of menu system, but if you really wanted to you could get at the CP/M prompt. This prompt, unfortunately, was the standard CCP, not any of the fancy ZCPR stuff that people running CP/M on Z80s were used to by then.

One thing that struck me during our conversation, and from many other conversations about computers in Swedish primary schools in the 1980s, was that the computers were very seldom used for anything! For instance, we were not allowed to use the computers to write texts! There were no word processor or text editor available, at least to my knowledge, and we were certainly not allowed to use the computers outside of specific “computer classes”.

This is particularly interesting if you look at the Microbee, since as far as I can tell all models had a built-in text editor!

We weren't allowed to use any advanced development tools either. On the Compis we had to write programs in COMAL, a language looking a lot like BASIC, but with proper procedures and functions. Really frustrating when I had the wonderful Turbo Pascal at home and I knew that Turbo Pascal was available on CP/M and for the Compis as well.

After our conversation I decided to look back at some development environments on CP/M and see if I could have lived with the environments back then...

I looked around for a Microbee emulator and found an emulator in Javascript, NanoWasp. Code on GitHub.

NanoWasp is unfortunately limited to a tape-drive system. It would be fun to work with something with floppy disk support. Anyone?

I didn't find any Compis emulators, but thought I'd look around for some more generic emulator to run CP/M on.

A popular emulator for CP/M seems to be the YAZE-AG Z80 emulator.

YAZE-AG comes pre-loaded with CP/M 3.1 and a lot of development tools. I was totally blown away by Turbo Modula-2! Look at drive M:.

Wikipedia tells me TM-2 was never marked by Borland but later became TopSpeed Modula-2 for MS-DOS. I had never used it before but it's really incredible. The environment is reminiscent of Turbo Pascal 3.0 with a small menu system and an WordStar-like editor, but the language is much richer.

According to this blurb the cost of TM-2 was $69.95. Tremendous value, indeed!

I would have been very happy indeed if this had been available at my school. I don't think TM-2 was available for CP/M-86, though, although it seems Logitech's Modula-2 compiler was. I think I would have been quite happy with just TP 3.0 as well, which was what I was programming in at home, but more important than this would have been access to the computers!