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.

We were impressed the board is still working. The typewritten manual looks odd today, and the board reminded us of a precursor of machines such as the KIM-1 and even the old Apple computer — the one that was also a small 6502 board and is now retconned as the Apple I.

We love these little peeks at old hardware. This would be a fun one to reproduce on a breadboard. The hand-drawn PC board shows there isn’t much to connect compared to almost anything you’d build today.

Watching [BradH] flip the switches, we couldn’t help but remember our own tour of the PDP-8. That one was an emulator, but we love [Oscar’s] recreation for doing real switch flipping.