ZiLOG Z80-CPU Technical Manual page 54

Flags
Symbolic
~
Mnemonic Operation C Z V S N H
DAA
Converts ace.
t t
P ~
•
~
content into
packed BCD
following add
or subtract
with packed
BCD operands
CPL A+-A
• •
• •
1
1
NEG
A+-O-A
~
t
V
t
1
t
CCF CY +-CY
~
• • •
0 X
SCF
CY +-1 1
• • •
0 0
NOP
No operation
• • •
•
•
•
HALT CPU halted
•
•
• • •
•
DI IFF +-0
• • • • • •
EI IFF +-1
• • • • • •
IMO Set interrupt
• • • • •
•
mode 0
1M 1 Set interrupt
•
•
•
• • •
mode 1
1M2 Set interrupt
• •
•
•
• •
mode 2
~
Notes: IFF indicates the interrupt enable flip-flop
CY indicates the carry flip-flop.
Op-Code
No. No.
of ofM
76 543 210 Bytes Cycles
00 100 111 1 1
00 101 III 1 1
11 101 101
2
2
01 000 100
00 111 111
1 1
00 110 111 1 1
00 000 000 1 1
01 110 110
1
1
11 110011 1 1
11 111 011 1 1
11 101 101 2 2
01 000 110
11 101 101 2 2
01 010 110
11 101 101
2 2
01 011 110
Flag Notation: •
=
flag not affected, 0
=
flag reset, 1
=
flag set, X
=
flag is unknown,
t
= flag is affected according to the result of the operation.
No.
ofT
States Comments
4 Decimal adjust
accumulator
4 Complement
accumulator
(one's complemen t)
8 Negate ace. (two's
complement)
4
Complement c
flag
4
Set carry flag
4
4
4
4
8
8
8
GENERAL PURPOSE ARITHMETIC AND CPU CONTROL GROUPS
>
TABLE
1.0-5
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