I remember the Z80 on the Altos 586 and 986 series... We ran Altos Xenix 3.0 on them... They used a Z80 for each set of 4 serial ports... But the main processor was an early x86 I think. That is the machine I learned *nix on! (it was better than MPM or Oasis (later called Theos))... (showing my age...) Larry Irwin