Full with additional links and infos, more than just a vintage computer museum entry:
To get an impression from what I’m talking – here’s an image from an M20 machine,
The machine was selled in 1982 with PCOS (that’s an operating system with cryptic commands, even more cryptic than CP/M was)…
There was an additonal 8086 card available to run MS-DOS, but that’s another story.
The cpu was – to document it more accurately – a Zilog 8001, the cpu family is named ‚Z8000‘.
Still one of the most „rich“ web pages about the Olivetti M20 can be found at