I thought technically it was the Commodore 128, which would run CP/M "incidentally" because they made an over-the-top promise of compatibility. The C64 had a C

I thought technically it was the Commodore 128, which would run CP/M "incidentally" because they made an over-the-top promise of compatibility. The C64 had a CP/M addon cartridge that was flaky at best, and the only way to get equivalent support was to just build a Z80 in.