The Ohio Scientific 300 Trainer

Hackaday on the OSI Model 300, which includes a video.

In the late 1970s there were a host of companies that dominated the computer market before the introduction of the IBM PC. One of these was Ohio Scientific or OSI. [BradH] has an OSI Model 300 trainer — their first major product — and gives us a peek at it along with some history of the company.

Companies like OSI, Southwest Technical Products, Osborne, Northstar, and PolyMorphic were the second wave after the likes of MITS and IMSAI had opened the personal computer market. Only a few companies like Apple hung on and made it work over the long haul.

If the history lesson isn’t for you, the technical talk starts at 4 minutes into the video below the break. This is a 6502 with 128 bytes of RAM. Not 128 megabytes or even kilobytes. 128 bytes. There’s a pretty traditional front panel with switches and LEDs.


My high school had an OSI Challenger 1P (I believe). But access was very difficult and it was kept in the Teacher’s Lounge. I wish I could have used it more than the couple of times that I was allowed to touch it.

But in a year, the school was officially teaching programming on Commodore PETs and access to them was much easier.

The Teacher’s Lounge was the only place within the school where teachers could smoke, and the Challenger eventually met its demise because of it.


I love the tiny 300! See also this thread elsewhere.

I think the 1P has a close relationship to my first machine, the Compukit UK101, which was a kit, and an unlicensed modified copy of the Superboard.

Ohio Scientific, based in Ohio, USA, were the makers of the Superboard II. The Challenger 1P and Challenger IIP-MF were essentially cased versions of this single board system with integrated keyboard, a single 5Volt power supply and the first 6502 version of Microsoft BASIC interpreter.


The video seems to have gone, perhaps because Brad has launched a new retro-specific channel. Here it is now:

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