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M > MSI > 6800   


The MSI-6800 system was a bus structured system based on the SS50 bus developed by South West Technical Products (SWTPC) for the 6800 processor in 1975. All of the MSI boards were thus compatible with all existing SS50 circuit boards and interface cards.

The main system had a 16-slot motherboard and was available ready-built or in kit form for some parts. It could support dual floppy disc drive (2 x 160 KB) which can be integrated into the main unit. It can also support a 76 MB hard disk unit.

The minimum system was made of one CPU board, one interface board and one 8 KB RAM memory board. If an optional 6809 board was used, this can be expanded to 384 KB.


More information from chuck hinkle:
I worked at MSI in 1977-79, and I still have a catalog of theirs.
The price was $595 for a kit (contained chassis & hardware, power supply, mother board & connectors), CPU board & monitor, 8K RAM Memory Board, Interface Adapter Board, Serial Interface Board). $895 for a wired & tested system.
We had two operating systems. One was co-written by Glenn Taylor and Ed Wells (who also wrote the last version of the Basic interpreter). The other was purchased/licensed from Software Dynamics. Robert Uiterwyk's BASIC Interpreter ran in FDOS, and SD-BASIC Compiler ran in SDOS.
MSI also marketed business systems with 5MB and 10MB Winchester Hard Drives, starting in 1979.

See the 'Advert' section for a full copy of the MSI 1978 catalog.

Please consider donating your old computer / videogame system to or one of our partners from anywhere in the world (Europe, America, Asia, etc.).


Chuck: I was the designer of the MSI 6800.
Any questions?

Tuesday 19th April 2011
Dana Peterson (Arizona)

The 1977 catalog from Midwest Scientific Instruments (featuring the MSI-6800) is available at

Monday 11th April 2011

Chuck $ Glenn: Correction: I worked at MSI from 1977 to 1979. I don''''t remember what your job was at MSI. Can you give details of what was your job? Thanks, Dana

Tuesday 12th April 2022
Dana Peterson (United States)


NAME  6800
TYPE  Professional Computer
YEAR  1977
KEYBOARD  Teletype or video terminal
CPU  Motorola 6800
SPEED  2 Mhz.
RAM  From 8 KB to 64 KB (384 KB with 6809 board)
ROM  4 KB (MIKBUG monitor)
TEXT MODES  Depended of the video terminal used
I/O PORTS  Serial RS232C, 2 x I/O ports
BUILT IN MEDIA  Tape recorder or floppy disc drive
OS  Flex with FDD version
POWER SUPPLY  Built-in power supply (18 Amp.)
PERIPHERALS  All SS50 based boards
PRICE  $595 in kit form, $895 assembled

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