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Welcome to the Ohio Scientific C4P page! The OSI C4P was the first real computer I owned. Let me digress. The first computer I ever touched was a Commodore PET; the one with the calculator keys and built-in cassette tape drive. I saw it at a Bay or Eatons in the mall. I was fascinated I started going to the local college's computer lab in the evenings to play with them. Eventually my high-school got some 4032 PETS to replace the old Wang machines we shared with another school. Anyway, I was hooked and couldn't get enough. I wanted my own computer and I started reading magazines and doing research to spend my hard-earned money on the "best" computer. At the time there was not a lot of choice; Commodore PET (no sign of the C64 just yet), Apple II, Atari 400/800, and Radio-Shack TRS-80. After comparing specs of all the machines I chose the OSI C4P because:
I purchased it in July 1981 (see invoice) and immediately started learning everything I could about the machine. I converted some PET BASIC programs, learned 6502 machine language. Eventually I upgraded the machine to 2MHz, added more memory and a floppy drive. I decided I wanted the computer and drive to be in one unit with a detachable keyboard so I started work on building a new case for it. I never completed it.
Of course as with all things computer related, bigger and better was just around the corner, but the OSI C4P was the machine that started it all for me. It is for that reason, and to preserve some of the glory days of the start of the computer revolution that I have created this page.
Eventually the OSI was packed away but not forgotten. Luckily I am a bit of a pack-rat and saved just about everything I had for the OSI. It is now 2006 and in the process of cleaning up my basement I have come across the stuff again. I have taken everything back out and am having fond memories of those days long ago. I found that I might have some stuff of interest so I am trying to document everything. I don't know how much I can do, so if you see anything here that interests you please drop me a line.
| CPU: | 6502 @ 1MHz, overclocked to 2MHz with simple jumper |
| RAM: | 8K expanded to 24K with D&N board |
| ROM: | OSI Monitor, Microsoft Basic |
| VIDEO: | Text 64x32 or 32x32 in 8 colours (or mono). |
| GRAPHICS: | None (use character set). Optional third-party hires board |
| SOUND: | Simple 1-channel Tone Generator, companding DAC (uses CPU to generate waveform). |
| STORAGE: | Cassette, expandable to Floppy Disk |
| KEYBOARD: | Basic 53-key keyboard |
| IO: | Joystick, Serial, Modem, IO ports |
| EXPANSION: | 4-slot backplane (2 used in base system) |
| CASE: | One-piece metal case with integrated keyboard and power supply. Wood-panelled sides. |
I have the OSI C4P with D&N floppy controller board and drive. I took the computer and drive out of their cases and planned to make a new all-in-one unit out of plexiglass. The top is missing and i never finished it.
The unit powers up but seems to have some problems with the video output. I tried connecting the system to my LCD TV but the display is very dim. It does give me the H/D/M? prompt and I can load OS65D3.3 and some of my other disks but things are hard to read. Because of this I haven't tested all my software yet. I will have to dig out a monochrome monitor to see if that works better.
The first two pictures were taken in 1981 and 82. They show my setup back then. The first one when I was using a cassette tape and monitor in case. The second after I upgraded to floppy drive and removed the guts of the monitor from the big bulky case so my system would take less space. By this time I also had my first Commodore 64 computer with cassette tape. The third picture is how my system looks today. I am planning to either build a new case with styling that matches the original machine or restore everything to original condition. The last picture is the machine running OSI Invaders on my 32inch LCD TV.
On the left is all the stuff I found in the basement in 2006. On the right, are my disks and tapes. I found my tapes about 2014 or so, and in 2018 I sent them off to another OSI'er to get backed up and archived. I have some manuals and binders containing schematics, docs, magazine clippings, and OSI-related newsletters.
In total, I spent about $3000 on my system, peripherals, software, and documentation as seen in this sheet I made at the time:
In 2006, after pulling my C4P system out of storage and getting nostalgic, I came across a guy selling his OSI system on a buy-and-sell site. It turned out he had a Superboard II (600 board) in a custom case, so I purchased it from him (along with a trunkload of Commodore 64 stuff as a bonus). It also came with some books, manuals, and newsletters. The 600 board is mounted in a metal case with wood sides all covered with fake wood-grain mactac. The top comes off for servicing. There are two toggle switches for tape operation.
Unfortunately the machine is not functional. When I get some time I will attempt to fix it.
In 2009 I picked up another C4P. This unit is the basic cassette model with an additional RAM board. The RAM board ia a clone of the OSI 527 24K board. Unortunately this unit is also non-functional. I have determined that the 502 CPU board is not working correctly and hopefully it can be fixed. I will update this page if I make any progress.
I purchased this unit to try to restore my system to original condition.
This is the TOSIE Hacker board. It added a new sound chip, extra ram and new character generator options. Attached to the bottom of the board is (I think) a Mittendorf high-res graphics board.
Thanks to Clint Cook for donating the BASIC and the Personal Computer book!
For a complete list of my documentation click HERE. If you are interested in more info on these please contact me. I will try to post rare, unusual, or requested documents here as time permits.
In mid 2018 I sent my entire disk and tape collection as seen above to a fellow OSI'er with a working system. He backed up everything that he could. Some disks were corrupted but it looks like a good majority of stuff was intact. I hadn't seen a lot of this stuff since the mid 1980's. You can find my collection here:
I would like to build a collection of monitor roms. If you have an OSI with a different ROM I would appreciate if you could send me a copy. I recently became aware of one called 'WEMON' which is supposed to add full-screen editing to the OSI, much like on the Commodore machines. Being a Commodore enthusiast as well I'm curious to see that in action! I also recently became aware of an 65816 cpu board. If you have one or have information about it, please contact me. Thanks!
I purchased the Aardvark C2E monitor rom for my C4P machine back in the day. When I updated my machine to use disk drives it seems to have gotten lost. I would really like to find this again. If you have a ROM dump please contact me!
I am looking to purchase a Superboard revision D (with colour video) and also a UK-101 board. If you have one to sell please contact me.
Last updated: Jun 2/2024, 2:00pm EST
Send comments or feedback to Steve Gray(sjgray@rogers.com)
