ZiLOG Z80 Handbook

capabilities of the 8008. In addition, Zilog has produced a family
of support chips that supplement the Z-80. The Z-80 is software
compatible with the 8080, allowing existing 8008 and 8080 software
to be executed on the Z-80. While the limitations of the 8008 and
8080 instructions and architecture must of necessity be retained in
the Z-80, the Z-80 offers new instructions, new addressing modes,
and new hardware features that provide more capability and versa-
tility than ever before.
800818080
Fig. 1-1
. Register comparison 8008,
8080, and Z-80.
z-80
A REGISTER FLAGS
A'
FLAGS'
B
C B'
C'
D
E
D' E'
H
L
H'
L'
INTERRUPT
VECTOR I
MEMORY
REFRESH R
INDEX REGISTER IX
IY
STACK POINTER SP
PROGRAM COUNTER PC
800818080
In addition to providing the eight 8-bit CPU registers of the 8080,
the Z-80 duplicates the eight registers to offer sixteen registers. Two
index registers offer indexing capability not provided in the 8080.
An interrupt-vector register and memory-refresh register provide
special interrupt functions and dynamic memory-refresh capability.
Fig. 1-1 shows the basic register arrangement of the 8008, 8080, and
Z-80.
Z-80 I
UNUSED
98
80 Z-80
INSTRUCTIONS
30 8080
INSTRUCTIONS
48 8008
INSTRUCTIONS
256 POSSIBLE
INSTRUCTION
TYPES (ONE
BYTE OP-CODE)
Fig. 1-2 . Instruction comparison 8008 , 8080
,
and Z-80.
13

ZiLOG Z80 Specifications

General

Manufacturer	ZiLOG
Introduction Year	1976
Clock Speed	2.5 MHz to 20 MHz
Data Width	8-bit
Address Width	16-bit
Instruction Set	Z80
Transistor Count	8, 500
Package	40-pin DIP
Category	Microprocessor
Memory Address Space	64 KB
Voltage Supply	5V