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General
DeKrlptiOD
The
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and
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CPUs are third-
generation single-chip microprocessors with
exceptional computational power. They offer
higher system throughput and more efliciel).t
memory utilization than comparable second-
and third-generation microprocessors. The
internal registers contain 208 bits of read/write
memory that are accessible to the programmer.
These registers include two sets of six general-
purpose registers which may be used
individually as either B-bit registers or as
16-bit register pairs. In addition, there are two
sets of accumulator and flag registers. A group
of "Exchange" instructions makes either set of
main or alternate registers accessible to the
programmer. The alternate set allows operation
in foreground-background mode or it may
be reserved for very fast interrupt response.
The Z80 also contains a Stack Pointer, Pro-
gram Counter, two index registers, a Refresh
register (counter). and an Interrupt register.
The CPU is e.asy
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mcorporate mto a system
since it requires only a single + 5 V power
source, all output signals are fully decoded
and timed to cc;mtrol standard memory or
peripheral circuits, and is supported by an
extensive family of peripheral controllers. The
internal block diagram (Figure 3) shows the
primary functions of the Z80 processors.
Subsequent text provides more detail on the
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1/0 controller family, registers, instruction
set, interrupts and daisy chaining, and CPU
timing.
+S\j'~
GND --..
CLOCK ......
Figure 3.
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CPU Block Diagram
2001·0212
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