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.