Morrow's MICRONIX Operating System

This document was last updated May 24 2011. To return to my S-100 home page click here.

Note: as of 2008, there are several firms which use the term "micronix" in their name or for a product or service. There are too many links to list here. If you are on this Web page in error, please use Web search engines to find the "micronix" you are looking for.


Micronix was a multitasking operating system for Z80 systems, first offered by Morrow in 1983. It was written to be "Version 6 UNIX compatible". Written in C (probably Whitesmiths C), it has a 64KB kernel and supports process spaces of 16KB to 68KB. The Version 1.61 manual I have describes it as installed on MOrrow Decision hardware, consisting of a DJDMA floppy controller, a hard drive controller of either an HDDMA (5.25-inch drives) or HDCA (8-inch drives), an MPZ80 CPU card, and a Wunderbus or MULTIO I/O card for serial and parallel ports. Memory was not specified, but is likely to have been Morrow's MM256K card with 256KB of DRAM.

The Micronix version 1.61 manual I have has a Forward page which lists the developers and is dated June 30 1983. Other dates in the manual are also mid-1983. There's just over 600 pages in this manual, with the following sections:
intro - 6 pgs
orientation - 14 pgs
installation & operation - 70
maintenance & admin - 95
tutorials - 16
programs - over 220
sub routines - 50
devices - 30
files - 30
other programs - 0

Morrow history

My Web page on Morrow S-100 systems is is linked here. George Morrow was an early designer of S-100 cards, and with others established the IEEE-696 standard for S-100 designs of the late 1970's. "S-100" refers to the 100 pin bus for Intel 8080 and later computers, first established with the MITS Altair in 1975. This site lists over 100 manufacturers of S-100 boards and systems; here is the home page for S-100 on this site.

Micronix owners, developers

We hope to have more notes and discussions here, from the developers and other former Morrow staff. Please contact me if you wish to contribute.

Marc Kupperand I discussed Micronix in 2006. More of Marc's discussion is on my Morrow Web page.

> Iirc, The Micronix project was started around 1979 with the first
> systems being sold in 1980 or 1981.  The MPZ80 was designed for
> and used for Micronix. Micronix was a full port of Berkeley Unix 
> and not just "Unix Like." I know by 1980 we had
> Micronix running....We used the Whitesmith C compiler both for
> Micronix and for the CP/M utilities.  

> In those days we [offered code as] what is now called
> "open source" meaning we gave people the source code to stuff,
> schematics, etc. when they bought hardware.  Probably the main
> exception was Micronix as Unix belonged to Bell Labs. 

> In a nutshell the Unix source code was free to universities and was
> $25,000 iirc for commercial users.  Morrow bought a commercial license
> meaning the base [Unix] V6 code's license would have been from Bell Labs...

- end quote -

Gary Fitts contacted me in late 2008. He says: "I no longer have any [Micronix] memorabilia, but I can tell you a bit about Micronix, which I wrote in the late '70s and early 80's."

"[My work began with writing] a very humble text editor and assembly language compiler for my Altair 8080. (It used a cassette tape recorder for file storage, driven by a TTL-level voltage output through a single diode -- everything else was in software.) I showed it to George [Morrow], whom I knew as a fellow grad student in mathematics at Cal Berkeley, and he adopted it to sell along with a 4K memory board. I believed we called it ATE (for Assembler and Text Editor, or something like that)."

"Meanwhile I was working on some numerical analysis problems, and I wanted more time than I could get on Cal's new Unix system. I wondered if it would be possible to build a powerful enough microcomputer system to host some version of a Unix-like operating system that I could dedicate to my research. I talked this over with George, and he began to design the hardware while I tackled the software. I did not port any existing Unix code. Rather, I designed a Unix "work alike" from the ground up, based on the system-interface specifications for Unix "version 6" and whatever public information I could find. "

"The best source, if I remember correctly, was "The Unix Implementation" by Ken Thompson in the Bell System Technical Journal, 1978. Meanwhile George designed a memory management scheme that intercepted the address bus of a Z-80 processor, and allowed us to allocate and map 4K chunks of physical memory into 64K virtual address spaces. When it all came together, we had a system that would reasonably support three users and dozens of independent processes. (Remember that this in the pre-GUI days, when it didn't take a lot of CPU power just to communicate with the user.)"

"Len Edmondson ported the Whitesmith's C compiler, and then most all of the publicly available Unix software tools. I remember the day when Len brought up YACC with almost no changes to its source. One of Len's most impressive achievements was a CPM emulator that ran on top of Micronix, allowing us to run popular CPM programs (such as Word Star) in our multiuser environment. This was a precursor to today's "virtual machine" world, where we can even host Windows on a Mac."

"As far as I know, Micronix was the only Unix-like multiuser system ever to run on an 8 bit processor."

"Those were the days!" - Gary Fitts

Micronix code

A number of Web or private archives of "CP/M" files and disks or disk images, especially Morrow files, also include some Micronix files. As of 2010, I don't have a particular distribution set of disks or images that are verified; I'm aware of some resources. But contact me if you are interested, or if you have Micronix disks available for imaging. It's a potential restoration project of mine to revive a Morrow and Micronix system.

Thank you. - Herb Johnson

Herb Johnson
New Jersey, USA
here is how to email @ me

Copyright © 2011 Herb Johnson