Re:Z80 arithmetic: also surprisingly terrible (2018)
by jonsen on Monday January 14, 2019 @04:29AM
(#18901805)
1 MHz clock on the 6800 family of processors, including the 6502, is equivalent to 2 MHz clock on the Z80.
The 6800 architecture used a so called two-phase clock. Each phase, positive and negative, of the clock cycle was used to do work.
However IIRC most contemporary architectures were closer to the Z80, so the 6502 was considered impressive because it was competitive despite a much lower clock rate.