Computing (FOLDOC) dictionary
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July 1976 with a 2.5 MHz
clock rate. The Z80 was a much
8-bit data and 16-bit addressing, and could execute all of the
8080 op codes as well as 80 new ones, instructions that
included 1, 4, 8 and 16-bit operations and even block move and
two banks of registers (including A and F) that could be
interrupt mode.
Like many processors (including the
8085), the Z80 featured
many undocumented op codes. Chip area near the edge was used
for added instructions, but fabrication made the failure of
these high. Instructions that often failed were just not
documented, increasing chip yield. Later fabrication made
these more reliable.
The thing that really made the Z80 popular was the memory
interface - the CPU generated it's own
RAM refreshsignals, which meant easier design and lower system cost.
That and its
8080 compatibility and
CP/M, the first
first choice of many systems.
peripherals and an
MMU to the Z80.
running at 4 MHz for GameBoy software or at 8 MHz for Game Boy
Color software. The Z80 was used in the
Sega Master System
(2003-07-11)