Mark's Ohio Scientific/Compukit UK101 Archive

OSI stuff.

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Ohio Scientific Inc. began in Hiram, Ohio around 1975. They were the first company to provide systems with Microsoft's floating point BASIC in ROM (1977), and by the time the company was sold in 1981, they had produced a number of systems both popular with hobbyists and used in small businesses. A fully expanded OSI system included options for home automation using a BSR X-10 AC interface, home security using a number of switch & sensor inputs, speech synthesis using a Votrax module, and DTMF decoding for phone applications. Storage started with inexpensive standard audio cassettes, the more advanced 5.25 or 8" floppy disk storage, or even a Winchester hard disk storage system. I/O included A/D, D/A converters, joystick, serial & parallel ports, EPROM programmers & prototype boards. Business systems could include a 3 CPU processor card which could run 6502, 6800 or Z80 software on a time share system with 16 terminals.

The UK101 was a version of the OSI 600 Superboard, similar to the one shipped in the C1-P, modified for use in the UK and Australia. The hardware was nearly the same, the system and BASIC ROMS began as modified versions of the OSI ROMS.
Thomas Buescher has a written nice OSI history overview here. Browse an OSI product pamphlet page 1, 2, 3, 4, 5 .
My introduction to OSI came in 1978, I was fortunate to get a C2-8P system, which looked something like this. It had an OSI 500 CPU board with 4K of 2102 static RAM 1Mhz 6502 & BASIC in ROM, a 540 monochrome composite video board with 2Kx7bit RAM & a 64x32 display + cassette interface, and a 420C 4K static RAM board using 32 2102A 1Kx1 static RAM chips, and a 9" B/W composite monitor. Total price was nearly $2000. Today you can emulate this system for free on your PC!

Emulator & Tools

This WinOSI Emulator is a rewrite of a UK101 emulator started by Ian McLaughlin at, later modified & supported by Thomas Buescher at

This version contains many changes and enhancements, including color support, 32/64 character wide screen support for C2/C4/C8 systems, and Tape & Disk image support. I wouldn't consider it complete yet, but it's probably further along than any other OSI emulators I've seen. Updates, enhancements, suggestions welcome!
Last update Nov-08-2015
32Bit Version for Windows 95+/NT+
WinOSI example application window
Click for larger view.

Emulator Files. See note at bottom before downloading.

File Description Size
The WinOSI Emulator for Win32 "prerelease" V1.5.2 Now Supports OS65U! (Next update soon!) 478k
The WinOSI Emulator for Win32 (Win9x/ME/NT/2K/XP), including BASIC and system ROMs, disk image, basic & machine programs, souce code, reference & tools. Supports 5.25 & 8 inch floppy disk images, and cassette.

Includes projects for MS DevStudio 6 and the free Borland 5.5 C++ compiler with the VIDE shell.
The WinOSI Emulator (same as above) in a self extracting archive! 656k OS65D V3.3 disk images for C1PMF 174KB
I had a hard time deciding what to do with these old copyrighted pieces of historical computing. I don't intend to infringe on the copyright or intellectual property rights of their owners, and will remove any file, or get the appropriate permissions, if the owner can be found. You are of course entitled to these files if you own the actual hardware.

All copyrights of any third parties referred to herein are hereby acknowledged. There is no warranty, either expressed, or implied, relating to any of the content contained herein.
You may use the information contained herein for NON-COMMERCIAL purposes only and AT YOUR OWN RISK.
Zip archive file: You will need to download a zip archive extraction utility such as WinZip, available at In order to extract these archives.

OSI Hardware

Ohio Scientific board image catalog

OSI Software

See the Collection of Ohio Scientific Software


Collection of reference materials
  1. Text file containing a list of known OSI hardware.
  2. Usenet message outlining the Kansas City Standard Cassette format which was used by OSI. (Don't miss Ed's conversion utility).


I am on the lookout for anything I can add to the OSI archive. Including:


Dave's OSI repository featuring message boards, scans & manuals.

Compukit UK101 Home Page featuring an OSI emulator for Windows, scans & manuals.

Ed's DX-Forth and Utilities Page includes a Kansas-City Standard audio decoder/encoder, which can convert sampled OSI tapes to binary.

Ohio Superboard II Emulator Homepage Thomas Buescher's WinOSI project, the genesis of this emulator

OSI Challenger 1P emulator & manuals

Mark S. Csele's Superboard web page including OSI pictures & advertisements

The 6502 resource page An archive of all things related to the 6502 microprocessor

Aardvark adventure games

Build your own UK101 with 11 ICs

MCC Workshop Comupter corner part 3 features pictures of an OSI 400 Series machine

You can send me feedback at email if you wish. Spam is not appreciated which is why the link is spelled out. :-(

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