MCM/70 (Spring 2023)

Manufactured By: Micro Computer Machines (MCM)

Conceived By: Mers Kutt

Release Date: 1974

The MCM/70 computer was conceived, developed, and built in Canada in 1974. It was arguably one of the very first "personal" computers because it was portable, had a built-in keyboard, display, and support for the APL programming language, plus cassette storage. On the other hand, at a cost of $10,000, it was only really accessible to large corporations, the military, governments, and educational institutions.

Based on the Intel 8008 microprocessor the MCM/70 had 32KB of ROM and up to 8KB of RAM. For output it used a Burroughs Self-Scan module, a 222 column by 7 row dot matrix display, capable of showing 32 5x7 dot characters at a time. Because the MCM/70 supported APL out of the box, the keyboard was based on the IBM 2741 layout. Finally up to two cassette decks were used for offline storage and to implement virtual memory.

The MCM/70's operating system consisted of two modules EASY (External Allocation SYstem), and AVS (A Virtual System) which were built into the ROM. These allowed the user to directly interact with the machine. In addition the ROM contained an MCM/APL interpreter. From cassette, APL application libraries could be loaded for finance, mathematics, statistics, education, and games. There was also printer and plotter support software.

I've been a vintage/retro computer enthusiast for a long time now and thought that I had a pretty good handle on all of the machines available in the 60s and 70s. So imagine my surprise when I saw the Kristina Panos February 23, 2022 blog post: INPUTS OF INTEREST: CANADIAN MCM/70 WAS KINDA LIKE THE FIRST CYBERDECK on the Hackaday site.

Kristina's blog post was a good place to start learning about the MCM/70.  It's a great summary of the origin of the machine, what it was, and its ultimate fate. I would encourage anyone with an interest in the MCM/70 to start there as I did.

For a more in depth look, the blog post references the book Inventing the PC: the MCM/70 Story by Zbigniew Stachniak. I purchased the book and really enjoyed it. A lot of the book is about the history of the company Micro Computer Machines which I found fascinating. More importantly, towards my goal of making an MCM/70, the book talks a lot about the design of the machine and provides insights into what ultimately led to that design some of which were technical, some practical, and some political.

Look. I would like nothing better than to find a dusty old MCM/70 computer for cheap in some thrift shop and restore it to it's former working glory. Realistically we all know how unlikely this is given that relatively few MCM/70s were ever produced and that it has been close to 50 years since the last one was made. 

So what about recreating the hardware from scratch. Obtain the original schematics and with luck PCB layouts, source the parts, many of which are vintage now and no longer manufactured, and make a replica. While this is might be possible, the endeavor would be very expensive, certainly well beyond the means of the average enthusiast like myself.

Another possibility is to create an emulation of the MCM/70 in software. This is just what the team at the The York University Computer Museum (YUCoM) did. From their web page:

An alternative approach to the direct use of MCM hardware  is to write historically accurate software emulators of this computer destined for modern desktop and laptop computers. Although such emulators do not necessarily reflect the computer's hardware on, say, integrated circuit level, they offer a platform for research of general hardware organization, storage organization, systems and applications software,  etc.

Software emulation is great and is certainly an important part of preserving these wonderful old machines, but I have found that nothing beats the feel of typing on a  physical keyboard and hearing the sounds of the keys clicking. 

So in the end I made a full size MCM/70 computer reproduction with a real keyboard and display which I integrated into the YUCoM emulator. This physical reproduction is quite accurate but was made with modern components and fabrication techniques. For instance, the case is 3D printed. I added “fake” cassette bays to give an authentic look and although they don’t house actual cassette drives, based on sensors in the cassettes they integrate with the virtual cassette drives built into the emulator.