MCM/70 - APL on an 8008 with just 8k RAM

Over in On the origins of Personal Computing I mentioned the remarkable and unique MCM/70, from 1973, with a one-line display, an 8008 inside, and an APL interpreter as the primary interface and application. And one or two integral cassette drives, used as swap devices as well as filestore, and to which the whole machine state is saved when shutting down… well, the amazing news is that there’s now an emulator for this machine, which includes the ROMs, allowing investigation of what must be a remarkable piece of programming.

Let’s just pause for a video, where we notice that memory is so tight the display memory is used as scratchpad during execution:

And note that MCM is mentioned already in a few old threads here:

I found the emulator by chance:

To obtain a copy of the emulator, please contact York University Computer museum at
museum at

Having sent my enquiry, I was delighted to get a reply, with an attached tar file, from Zbigniew Stachniak himself, who wrote the book on MCM/70 - see below.


For those finding the book to be a bit expensive, the same author also wrote an article on this topic in the IEEE Annals of the History of Computing, “The Making of the MCM/70 Microcomputer.” There’s also a video of a presentation he gave.


From the article:

Wow. I hope it made calculating sounds and had blinking lights while it was processing. Imagine doing matrix work on this thing. Obviously, it’s “better than nothing”, but…wow.

The MCM/70 is a great machine that was ahead of it’s time and very much like a mainframe on our desk. The video above is my MCM/70. There is a further video where I type in an APL program for a game of “Horse” shown here:

The video’s were actually made to check how close the MCM/70 emulator was to the real computer. Zbigniew was right on.

For the record, no calculating sounds. There was nothing mechanical in it as you will see. However, I did type loudly so the timing could be captured :slight_smile:

You can see further pictures of the computer and internals at my site at MCM/70


Excellent! Great to see you here, and to hear that the emulator is spot on.

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I also enjoy the MCM70 User’s Guide as a gentle introduction to APL.


Nice machine! I don’t know how I have lost this post, now I want to play with the MCM/70 and APL :slight_smile:

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Taking it one step further, here is the York University emulator ported to Windows

and an early proof of concept of it ported to the Web/WASM



Welcome, and what a marvellous project. Has it led to any better understanding of the firmware?