Cromemco S-100 computer ~ a Silicon Valley memoir (1977-1997) by Robert C. Kuhmann

This page last updated Jan 22 2008. (c) Herb Johnson except quotes from Robert Kuhmann.

Robert C. Kuhmann was an early customer of Cromemco, and knew the founders. He built an early bulletin board system from Cromemco products. Robert provided a "memoir" to me on Jan 2007 of his Cromemco-related activities, which is quoted below with permission. Check his Cro'sNest Web page on his site for more information. or to contact him . - Herb Johnson

The Cro'sNest RCP/M-RBBS

"The Cro'sNest RCP/M-RBBS" (Remote CP/M Bulletin Board System) "Cromemco" based, S-100 micro-computer, Built and maintained by: Robert C. Kuhmann, Sysop. This machine was in continuous 24x7 operation, from 1977-to-1997.

"The idea and the desire to build this particular S100 computer evolved from the fact that the Cromemco founders were both at Stanford University (grad students at the time). My ex-wife, Nicole and I were also on-campus from 1974-thru-1978. I was working as a microchip designer at EXAR (Sunnyvale,CA -- from 1974-1981). In 1976 my supervisor (Yoshiji Kurahashi) bought a [Cromemco] Z2D. I too was quickly sold on the qualities of the Cromemco product line! My "Cro" was assembled at my "Skywest" home located next to the Hayward,CA airport. We then moved to Sunnyvale where my "Cro" began it's role as one of the FIRST remotely-accessible, private computers in the world. It had a total online storage of 1.8 Mega bytes (4 floppies, no hard drive)."

"In 1983 it traveled with us to France -- where it continued to serve European enthusiasts -- until 1997, whereupon I returned to the USA. This computer became the basis for a computing "club" that I founded in France, called PicoNet France. The organization quickly grew to more than 2500 members. That activity evolved into my first founder's business, WildWest SARL. " - Robert C. Kuhmann - from his memoir, 21 December 2007

Components of this RBBS were either built by RCK or bought new, and were as follows:

Cromemco, "ZPU" (4mHz Zilog Z80 CPU board) 1976 - purchased new.
Cromemco, "PRI" (dot-matrix/daisy-wheel, parallel printer interface) 1978 - purchased new.
Cromemco "16FDC" (5" & 8" floppy disk drive interface, boot PROM and serial interface to the console) 1979 - purchased new.
California Computer Systems "CCS-2065" (64K RAM board- rev B) assembled
PMMI "MM-103" (300 baud modem) purchased new.
CompuTime - "QT Clock" (purchased as a kit) assembled
Heathkit "H19" (serial terminal, black & white) purchased as a kit, assembled by RCK
Epson "MX-100" (132 column impact printer, B&W ribbon) purchased new.
Shugart "SA-400" (DSDD 5"1/4 floppy drive - 2 each) purchased new.
An external case and power supply was built from parts by RCK.
Siemens "FDD-100-8" (8" SSDD floppy drives, 2 each) purchased new. Adapted to work in lieu of Persci 8" drives (as used by Cromemco Inc).
S100 (chassis, power supply, cooling fan) purchased a new SD Systems 'bare-bones' model (looked a lot like the above).

Photos of the above are on Robert's Web site at this link. The final result was the "equivalent" (technically) to a Cromemco Z2, a factory-built 19" rack-mount machine, but with 8" & 5-1/4" drives -- 2 of each.

History of Cromemco, from Robert Kuhmann

Note: minor edits by Herb Johnson are in []'s. OTherwise this text is as provided Jan 2008 from Mr. Kuhmann. - Herb Johnson

Cromemco was a Mountain View, California microcomputer company known for a series of high-end S-100 bus computers in the early days of the microcomputer revolution. Their machines were also known for generating computer graphics for television stations. [They produced systems used by the US military, and by companies and institutions around the world. Companies descended from Cromemco still exist in the 21st century.]

The company began as a partnership in 1974 between Harry Garland and Roger Melen, two Stanford PhD students. The name comes from their residence at Stanford University, Cro(thers) Mem(orial), a Stanford dormitory reserved for graduate students. The company was incorporated in 1976.

Their initial products used the Zilog Z80 microprocessor and the S-100 bus. The Z-1, released in August 1976, was a Z80 development system on a heavy-duty IMSAI 8080, 22-slot chassis. It included 8KB of static RAM, an RS-232 serial port, and a PROM programmer, and sold for $2495. Its modular design supported a 4MHz Z80 plug-in card ($395) and 4 KB static RAM cards ($295). The 1978 Z-2 line was an updated S-100 computer sold as modules or a complete system. The Z-2 was available with one 5-1/4 inch floppy disk drive and no RAM for $1995 or as the complete System Two (CS-2) with 64KB RAM and two floppy drives for $3990.

The Z-2 was the first commercially marketed microcomputer certified by the U.S. Navy for use aboard ships without major modification, and some were used aboard Ohio class submarines for data logging during tests. The System Three (CS-3) was the "professional" version of the System Two with two 8-inch floppy drives standard instead of 5-1/4 inch drives, and 32KB RAM for $5990. The Cromemco 3101 serial display terminal was a re-branded Beehive Medical Electronics B-100 terminal./

The System Two and System Three were sold to educational establishments across Europe and China. These sales helped the company to fund the transition to 16-bit systems with Motorola MC68000 processors during 1981. The System 1 followed the System Two and System Three. It contained either dual 5 1/4 inch floppy drives, or one floppy and a 5 MB hard disk, and was available with a dual processor "DPU" card which contained both Z80 and MC68000 processors.

A ruggedized version of the MC68000 computer with removable hard disk cartridges was widely deployed by the USAF as part of the USAF Mission Support System (MSS) for F-16, F-15 and other aircraft. The MSS provided pilots key navigational and other data during missions and enabled combat pilots to compare mission effectiveness to flight plan data during the subsequent debriefing by their superiors.

The C-10 personal computer was introduced in June, 1982. It was a 4MHz Z80 system featuring 64KB RAM with an 80 character × 25 line video screen for US$1785.

During the mid to late 1980s, Cromemco produced the graphical microcomputers used by many television stations for weather forecasts.These Colorgraphics Systems were used on the evening news programs to replace the transparent acrylic glass maps on which local weathermen formerly drew weather symbols by hand. The computers used an enhanced version of Cromemco's popular Dazzler color graphics card.

[Regarding operating systems,] the Z80 based systems ran either CDOS (Cromemco Disk Operating System) or CP/M. Multi-user capability, via their own Cromix operating system based on Unix, was offered from 1979 onwards. Roy Harrington was the lead designer of the Cromix development team. Cromix was written in the C programming language to run on an 8 bit Z-80 processor. It included many of the properties of the Unix operating system which typically required a sixteen bit processor with a hardware memory mapper (that the Z-80 did not provide). The Z-80 processor was able to utilize up to 16 banks of 64KB of RAM to support 1MB multi user and multitasking applications. It was possible to run this efficient operating system using only a floppy disk drive (no hard disk). That distinguished [Cromix] from other operating systems of the time based on Unix which required large expensive hard drives.

At its peak in 1983, Cromemco, Inc. employed, more than 500 people and had annual revenues of US$55 million. It was wholly owned by Garland and Melen until it was sold to Dynatech in 1987 as a supplier to their subsidiary, Colorgraphics Weather Systems. The European division of Cromemco reorganized as Cromemco AG ...and is still in business (ca. 2007)!/

And so it was... 30 years ago! - RCK,

Cromemco Web sites

Standford University has a museum which displays some Cromemco products, among other items from their alummni. They have a Web page which discusses Cromemco, its founders and some history, at this Web link.