The Micromint SB180 by Steve Ciarcia

Welcome to the SB180 Survival page! Here you will find information on what the SB180 computer is, the software it uses as well as a few pointers on resources. (AFAIK, this is the only SB180 web page I know of.)

Help Save the World!

Got some docs in electronic format? If you're willing to contribute, please feel free to and I will post them here for the benefit of other SB180 survivors! I am also looking for info on some of the more obscure boards, for example, the GT180 and the memory expansion board. Pointers to software and notes about ROM modifications and such would also be appreciated!

What is the SB180?

The SB180 is a single-board, HD64180-based (Hitachi-enhanced Z80 CPU) CP/M computer which first appeared in the September and October 1985 issues in Byte Magazine. It's probably better described by Micromint's original specsheet.

The operating system that the SB180 used was the Z-System, originally made by Echelon, and then passed onto others when the company decided to refocus its resources towards networking products.

Believe it or not, the HCS-II home automation controller and the SB180 are actually distant cousins. The HCS-II was derived from the Micromint RTC180, which is similar to the BCC-180. The BCC180 in turn is actually an SB180 without disk I/O, and targetted towards the industrial embedded controller market. Both the RTC-180 and the BCC-180 are still sold by Micromint.

SB180 Board Revisions 1 and 2

The original SB180 as pictured and presented in Byte Magazine was a Rev. 1 board (but it wasn't marked as such). Later on Micromint produced a new board, marked REV 2.0. This board includes a new capacitor across pins 1 and 2 of U21 (74LS240) and a diode across pins 18 and 4 of U21 (with the black band towards pin 4). Additionally, the 34-pin floppy connector was moved further to the edge of the board to allow for a right-angle connector. It's most likely that the SB180LO (mentioned below) is a REV 2.0 board.

What is the SB180FX?

The SB180FX is an enhanced version of the original SB180. It included the following:

Essentially, it was a SB180 combined with the COMM180 (see below) and an extra 8255 for digital I/O. This board was designed in response to an incorrect assumption by Steve Ciarcia that only one board would ever be stacked on the SB180 - he hadn't counted on having more than one.

The SB180FX was never presented in Byte Magazine, but was first mentioned in the November 1986, December 1986 and January 1987 issues of Byte Magazine as an item for purchase from Micromint. It also managed to get a blurb in the "What's New" section on page 36 of the December 1986 issue of Byte. Incidentally, those issues of Byte described the GT180 graphics board (see below).

What is the SB180LO?

The SB180LO came out several years after the SB180 and to the best of my knowledge, was simply an industrial temperature-tolerant version of the original SB180FX.


COMM180 for the SB180

Soon after the release of the SB180, came the COMM180. The COMM180 was a stackable board that allowed you to plug it into the 40-pin expansion header of the SB180 and added both a single-chip modem and a SCSI interface.

GT180 for the SB180FX

The GT180 was a graphics terminal board made just for the SB180, and like the COMM180 was to the SB180, the GT180 was a stackable board meant to interface to the SB180FX's expansion header. It used fairly hefty (for the time) Hitachi graphics chips to drive the PGA-like resolutions it could produce. As already mentioned, the GT180 graphics board was first introduced in the November 1986, December 1986 and January 1987 issues of Byte magazine.

The maximum screen resolution of the GT180 was 640- by 480-pixels at 16 colors. The board's oscillator, however, could be interchanged with others at different frequencies to produce what approached PGA-like resolutions and color depths.

SB180FX-MME for the SB180FX

The SB180FX-MME was a memory expansion board for the SB180FX. It shipped with 256K of RAM, but was socketted to support up to a total of 2MB.


This was a high-performance board for the SB180. It added many hardware features, most of which are reminiscent of the SB180FX features. This board was made available in co-operation with the North American One-Eighty Group (NAOG). More info is available .

Hal Bower contributed the following blurb about this board:

Since source code for the boot ROM was provided on diskettes with the SB180, it is easy to include additional routines that will check for a bootable SCSI drive as well as floppy diskette. The same chip (NCR 5380) is used in both the COMM180 and ETS180IO+ and are wired to the same base address, so the same ROM code may be used with either expansion board. The new routines are written in a compatible manner to the Floppy boot code, and called from within the scanning loop that tries several times to boot from floppy before jumping to the monitor section of code. As modified, whichever of the Floppy or SCSI becomes active first will boot the system.


SB180 and SB180FX

The SB180 and the SB180FX boards both used Echelon's Z-System. The Z-System was basically an OS suite, which was a superset of CP/M 2.2. It contained many enhancements, most notably ZCPR3. The October, 1985 issue of Byte Magazine contained a summary of


The GT180, in kit form, came at least with a demo disk. However, the complete package came with Borland's (yes, that's right, Borland) Turbo Modula-2 and the Borland Graphix Toolbox. Both were specially ported to the SB180 and the SB180FX.



The SB180/SB180FX/SB180LO are no longer made by Micromint. Some SB180's have been seen on E-Bay, while folks on comp.os.cpm have been known to post a note wanting to sell complete SB180 systems, or just bare boards themselves.


Echelon no longer makes or sells the Z-System, as this was passed on to others. Don Maslin of TCJ fame sells copies of the Micromint SB180 Z-System disks for a modest fee. Here's a list of other system disks he has made available.

There's also a few places on the Internet where you can still find some user-contributed code for the SB180 and the Z-System.


This is becoming especially critical, given the age of the boards, static damage that occurs from time-to-time, and MTBF's. The goods news is that most of the chips on SB180 boards are still available for purchase on the street. So let's focus on the ones that aren't so plentiful....

FDC 9266

Standard Microsystems Corporation was the maker of this enhanced floppy disk controller. Unfortunately, they ceased production in the mid-90's. There are at this time of writing just two sources now:

Obtaining parts from either of these two companies is an exercise unto itself but not entirely impossible. Just keep at it and eventually they will get back to you.

HD 64180

The HD 64180 was made by Hitachi Semiconductor. Hitachi still makes this CPU, however, Zilog licensed (I believe) the dies from them, and have since then created new variants on the HD 64180. The Zilog part number for the HD 64180 is the Z80180, or Z180. The other neat thing about it is that you can probably increase the speed of your boards by using the newer 18MHz parts. Since my SB180 isn't completely functional, I haven't tried this myself yet, but it is worth a try!

In fact Paul R. Hunt wrote-in that he had actually experimented with this.

256k Memory Chips

These ones I haven't really tracked down myself, but I suspect that they're not produced anymore either. The part numbers for these varied. Some examples are:

I suspect that the obsolete parts distributors listed above may have these. They may also have faster memories for those wishing to overclock their SB180's.

Chip Resources and Specs

HD64180 and Z180

FDC 9266

Public software Archives

Forums for Discussion

The SB180 gets some discussion from time to time on comp.os.cpm. The Circuit Cellar BBS itself was once a hotbed of activity for anything Circuit Cellar did. It's now defunct, but its successor, - a newserver - now more than easily handles that function. Steve Ciarcia himself lurks there too. Simply subscribe to the newsgroups there as described at the Circuit Cellar Newsgroups page.

Last updated: January 16, 2002

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