Morrow Micronix

6th Edition Unix on a S-100 Bus Z80

Morrow Designs built a very sophisticated Z80 CPU card, the MPZ80, in the early 1980's, and a talented team led by Gary Fitts put a pretty good clone of Unix 6th Edition on it. The Z80 was pretty underpowered at 4MHz to pull this all off, but it did work. I picked a working machine up for next to nothing in the late 1990's, but got rid of it after playing with it. The media and circuit boards, along with the case itself, disappeared into the mists of time.

Enter the late second half of the second decade of the twenty-first century, and it's apparent that this was quite the engineering achievement and triumph of imagination. A more or less vibrant market in retro equipment of this era can be found on EBay, and some of the bits are available in various collections. I've accumulated enough of the right kind of hardware to resurrect Micronix of some version, and the barriers to getting there seem surmountable.

Before embarking on this, I decided to see if the binary artifacts that are on the net are usable or complete. Apparently, a large number of disks from Ron Jacobs, a former Morrow engineer, are preserved on the net, and contain fragments of Micronix 1.3 and 1.4 binaries, and the Micronix 1.61 source code. The MPZ80 boot ROMS in both the CP/M and Micronix versions are available in source and binary. Additionally, the DJ-DMA, a very advanced floppy controller, along with a HDC-DMA, the corresponding hard disk controller, also now exist in my Hardware collection.

I placed copies of the extant Micronix artifacts onto and added the publicly available Unix 6th and 7th edition archives for reference and to augment any lost sources.

My object is to build a user mode simulator capable of running micronix binaries, then, a simulator capable of running the stock kernel, and finally to bring the real hardware up. The first task is essentially done.

Update: the github repo reflects a much different directory layout, and the user sim is capable of compiling and linking a micronix 1.61 kernel.

Credit where Credit is due:

Please be aware that this builds on the tremendous work of others, notably the collection of Herb Johnson,, Dave Dunfield,, and whoever curated Additionally, the people who finally freed the classic unix sources are deserving of huge appreciation. Finally, Dennis, Ken, Brian, and Stephen, who started it all.

Special thanks to Morrow Designs staff: Gary Fitts, Len Edmonson, and Ron Jacobs, who at various times were helpful and inspirational.