Yeah, i'm restoring a Compucorp 625 at the moment, which was made in 1978 and is Z80 based - not a bad run!

I guess we should really applaud the Intel 8080 for starting this, but probably the brilliance of the Z80 was simplifying the external requirements. The 8080 required +5v, -5v and +12v, and I think some external clocking and DRAM refresh, whilst the Z80 was just +5v, and integrated clocking and refresh to get the component count down.