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C > CROMEMCO  > System I / II / III   

System I / II / III

CROMEMCO was founded in 1974 by two Stanford Students, Roger Melen and Harry Garland, who lived in the CROthers MEMorial Hall dormitory on the Stanford campus.
Eventually CROMEMCO needed space to receive visitors, and moved out of the dorm to Mountain View, and incorporated in 1976. Early products were cards for the S-100 bus, as used by the Altair and IMSAI computers.

These computers were built around the S100 bus. The S100 BUS was a standard (also known under the name IEEE 696) for connection on Zilog Z80 or Intel 8080 processors. A lot of S100 cards were available for the Cromenco systems.

Four Cromenco systems were available :

- System 0: Z80 A + RAM 64 KB + 2 floppy disk drives (390 KB each),
- System I: As system 0 + 1 hard disk (5 MB).
- System III: Z80 CPU, Dual 8" Persci electrically driven floppy drives, 64 KB RAM. It was S-100 bus, Multiuser, used MP/M operating system.

In 1982, Cromemco also introduced the CS-1H system using a dual processor board (Motorola 68000 and Z80) and offering 16 MB of address space.

For the moment, we don't know exactly the specific features for the Systems II and IV.

These systems ran under Cromix (the Cromenco Unix version). They could run under CP/M and CDOS too (CDOS is a CP/M like operating system). Several languages were developped especially for these computers : Fortran IV or a 16 K Z80 Basic wich was given as "one of the fastest and most capable. Full 14-digit precision".

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My first job was with Cromemco (employee $58).
The Cromix system shared 16KB between the 8 banks of 64kB max memory, it had the OS. Bank 0 had ??kB memory and the whole OS, banks 1-8 had the user 64k with 16k disabled or 16kB memory cards offset to 16kB and higher. Also came out with a 48KZ memory card so that nothing was wasted.
Fast since a lot of stuff was Z80 assembly.
The real hot sw was the 32kB structured BASIC. It had everything and was all assembly, it was stuffed into 32kB of 2116 EPROMs! So fast the business apps were written using it as I remember. You could run interpeted or complie the code.
Oh, Cromemco also had the first C sw on a micro. I rememeber compiling a ''Hello'' program and it was an incredible 5kB!!! Talk about memory hog!! He he, the old days back when you counted Bytes...

Sunday 27th November 2011
Ian Yoch (USA)

I upgraded a Cromemco System III in the early 1980''s for NASA. It used the MP/M O/S. We supported 6 users at one time with 6 terminals and 5 printers scattered among the secretaries for the division. I believe it had two hard drives. I believe there were 7 64KB memory cards. Each of the 6 users had 62KB of RAM dedicated to them. Wordstar was used by each secretary for word processing. It is amazing to think back how one Z80 CPU at 4MHz could support 6 people at one time each running Wordstar.

Thursday 29th September 2011
Edward Kenny (Huntsville, AL (USA))

Our Company used two Cromemco System IIIs and I bought an old Cromemco system personally. Both of the IIIs had twin 8" drives which eventually failed. We bought them in 1981/82 and kept them in use until about 1986/7 when we bought a Compaq 286 as a dedicated server (running Novell 2.0a.) with two Compaq PC/ATs as workstations running CP/M and MSDOS. The Cromemco systems had 4 16KB S100 ram boards and the other boards were processor, serial & parallel I/O & drive controller. Televideo terminals (monitors with attached keyboards) were used to interact with the system boxes. We ran CDOS (the Cromemco DOS) and CP/M as operating systems with Wordstar, Calcstar, Datastar and Supersort. I set up a rudimentary stock control and invoicing system using the application software. We also dabbled with an operating system called BOS and ran an accounting package under BOS. I also obtained a copy of Cromix which was a multiuser UNIX-like operating system but, without a hard disk, this was not very successful. I believe we still have the system boxes on a pallet at the back of our warehouse and at some stage (when I retire?) I'll try to get it all working.

Sunday 1st May 2005
Peter Harding (UK)


NAME  System I / II / III
TYPE  Professional Computer
YEAR  1976
CPU  Z80
RAM  32 KB (up to 512 KB with a pagination mechanism)
ROM  Unknown
GRAPHIC MODES  754 x 482 monochrome / 377 x 241 16 colors. A special video card was available with 3 video processors which allows the same resolutions but respectively with 8 and 4096 colors.
I/O PORTS  8 bit ADC or DAC, Centronics, Disk controller, S100 Bus, 21-card-slot
BUILT IN MEDIA  Varies according the model

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