January 22, 2022
- I've begun digitising and uploading OSI C1P software from my grandfather's old audio cassettes.
- Here are the tapes I've uploaded so far (Google Drive folder, most recently updated on 2024-06-18).
- I'll get around to a proper web page for it, you know… later.
- My C1P suffered a video fault - replacing U40 (one of the two video RAM chips) fixed it.
- For reference, here's a video showing the symptoms.
November 14, 2021
Two bits of unexpected news!
- I've managed to buy a beautiful, unmodified 8K OSI C1P in an online aution. It's actually this one, formerly owned by collector Terry Stewart. It's here with me now, and works perfectly. Oh my gosh.
- At the end of 2020, my uncle found twenty-ish audio cassettes filled with C1P software in his garage. (Actually, I noticed them in his trailer headed for the tip! The timing was pretty amazing — I don't visit all that often!)
April 21, 2020
So, I've been working on an emulator for the OSI C1P, UK101, etc.
In case I get popped by hedgehogs or fall into a vat of glue, here's a first release of the source code. It's written in plain C and requires SDL (well, not really, but if you want graphics…). Here's a YouTube video showing what sort of state it's in.
There's lots to improve, but the main annoyance is that writing/saving files isn't yet implemented.
- osi65-1.0-20200510-020557.tar.gz (98 Kb) - C source. I'm just gonna keep updating this occasionally as I tidy things up - see the filename for the date of upload.
- osi65_data.tar.gz (47 Kb) - C1P and UK101 ROMs, plus bits and pieces.
- osi_c1p_manuals.tar.gz (46 Mb) - O.S.I. C1P reference manuals in PDF format.
Note: The data tarball contains three subdirectories: fun, machines, and software. If you copy those directly into the source code's main directory, osi65-1.0, things should "Just Work". The emulator is GPL'd, but the ROMs are of "uncertain" status — hence the separate tarballs.
July 2017
I've started working on an emulator for simple 6502 based machines like the O.S.I. and Compukit microcomputers. The emulator is written in C, and I'll release it under the GNU GPL version 3 once it's a little more complete. It already runs pretty well and is able to load O.S.I. Superboard II / C1P (and UK101) software, including the O.S.I. Invaders game that prompted me to start this page (see below). At the end of this page you'll find links to other O.S.I./Compukit emulation projects and related information.
September 2016
Clearing out the garage, I found a cassette tape from 1978 containing O.S.I. Invaders
for the Ohio Scientific Inc. Challenger 1P. I spent hours playing this when I was a kid. Best Space Invaders clone ever! (Okay, not a clone exactly, considering the C1P's character-based graphics, but the play is amazingly good, and fun.)
I dug out a dusty tape deck, plugged it into my PC, et voilà! Digitized! Now all I need is a C1P. (Actually, Google turns up some emulators (links below), but a non-proprietary one would be best… No, wait, an actual C1P would be best.)
Download
- SCG-971-OSI_INVADERS_C1P.zip (62 Mb - includes the unedited WAV, plus a decoded version made using Mark Ward's Kansas City Tape Decoder)
Here are the notes my grandfather wrote on the paper liner:
BREAK M Start recorder Press L (Takes 12 minutes) Puts in machine language and then lines of BASIC Self starting ?FRE(U) = 224 LOADER 000 - 011 MACHINE CODE 011 - 140 BASIC 140 - 175
Records: 42910 by Tim, level 15, 15/12/81 28250 by Tim, level 5, 2/3/81 18830 by Tim, level 4, 30/11/81
Elsewhere
- Wikipedia: Ohio Scientific
- Dave's OSI repository and forum
- Mark's OSI and Compukit archive
- Terry Stewart's (Tezza's) Classic Computer Collection and superb YouTube channel
- Jerry Travis's Ohio Scientific (OSI) Challenger 1P (C1P) Superboard Page
- C1Pjs is a GPL'd C1P emulator in JavaScript. The site includes user manuals in PDF
- Tim Baldwin's BSD licensed Compukit UK101 Simulation in Java can also emulate the OSI C1P
