Sardis Technologies ST-2900 Computer System

(This page is still under construction.)

The ST-2900 is a small computer system I designed around the Motorola 6809E 8-bit microprocessor. It can be configured as a 1-board, 2-board, or 3-board system, depending on requirements.

The ST-2900 started shipping in June 1984, and was sold world-wide for several years. Although sold mostly as bare boards which were assembled by the users, some were also sold assembled and tested, or in custom configurations. And, yes, a few people are still using the ST-2900, more than 35 years later!

I ported four operating systems to the ST-2900: FLEX/6809 from TSC, STAR-DOS/SK*DOS (6809) from Star-K Software, OS-9/6809 Level I from Microware, and recently, NitrOS-9/6809 Level 1.

The ST-2900 was reviewed by the editors of '68' Micro Journal on pages 15-17 of the December 1984 issue. An update to their review appeared on pages 27-29 of the February 1985 issue. Finally, the November 1985 issue (pages 48-50) printed my response to their review, and provided detailed information on upgrading to newer versions of the OS-9 Conversion Package and ST-MON.

For many years I used two ST-2900 systems as my main computers, before finally capitulating to the world of Intel x86 and Microsoft MS-DOS and Windows.

My last remaining inventory of boards and components was sold to a customer in the UK in 2017. If you are interested in purchasing any boards or components, contact me, and I will forward your request to this person.

This last sale required that I also deliver the related software. But it had never been copied from the original 5" floppy disks onto more modern media, and I hadn't read those old disks in many, many years. In order to ensure the best possible chance of successfully reading data from these disks, I developed the UFDR hardware and software.

More detailed background information on the ST-2900 is provided in The ST2900 Story.

(Click on a picture for a larger version.)
Advertisements in '68' Micro Journal (2MB .png).

ST-2900 System Brochure.
(3.6MB .pdf scanned image)
The ST-2900 CPU board can run by itself as a single-board computer. It has a 1 MHz 6809E microprocessor, 2 serial ports, one 16-bit counter/timer, up to 7 input and 8 output lines, 16KB or 64KB DRAM, and a 2732 (or 2764) EPROM containing the ST-MON monitor program.
The ST-2900 FDC expansion board plugs into the CPU board. It has two 8-bit parallel ports, two 16-bit timers, and a floppy disk controller, allowing it to run disk-based operating systems. A prototyping area fills the remaining space.
The ST-2900 RAM-512 expansion board installs between the CPU and FDC boards. It supplies 512KB DRAM as 128 4KB pages to implement a RAM-Disk.
The ST-2900 FLEX Conversion Package adapts the TSC FLEX/6809 and Star-K Software STAR-DOS/SK*DOS (6809) operating systems to run on the ST-2900 hardware.
The ST-2900 OS-9 Conversion Package adapts the Microware OS-9/6809 Level I operating system to run on the ST-2900 hardware.
The ST-2900 NitrOS-9/6809 Package adapts the NitrOS-9/6809 Level 1 operating system to run on the ST-2900 hardware.
Diskless operation of the ST-2900. Allows booting and running OS-9, NitrOS-9, FLEX, and SK*DOS operating systems, even if no disk drives are connected.
Other ST-2900 software implementing floppy disk track caching, a ROM-Disk, etc.
(not available yet)

"FLEX" was a trademark of Technical System Consultants (TSC).
"STAR-DOS" and "SK*DOS" are trademarks of Star-K Software.
"OS-9" is a registered trademark of Microware LP.
"MS-DOS" and "Windows" are trademarks of Microsoft Corp.

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Last revised 2020-Jun-23 08:57 PDT.
Copyright 2020 by David C. Wiens.

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