The result is a $4 Z80 home computer, and a great Hackaday Prize entry to boot. So, what do he need to build a retrocomputer loaded up with Forth, CP/M, and Basic? A CPU is a necessity ...

It was called the Z80 SoftCard, and it was first released 43 years ago this month, on April 2, 1980. In an even more ironic twist, the product was made as an add-in card for the Apple II PC.

Back in the 1980s however, you generally had little choice: a certain home computer came with a certain OS, and that was it. If yours was based on a Z80 processor, chances are it ran CP/M.