Zilog Z08470 - Manual (Page 183)

UM008007-0715 Z80 Instruction Description
Z80 CPU
User Manual
171
DAA
Operation
@
Op Code
DAA
Operands
None.
Description
This instruction conditionally adjusts the Accumulator for BCD addition and subtraction
operations. For addition (ADD, ADC, INC) or subtraction (SUB, SBC, DEC, NEG), the
following table indicates the operation being performed:
Operation
C Before
DAA
Hex Value
In Upper
Digit
(Bits 7–4)
H Before
DAA
Hex Value
In Lower
Digit
(Bits 3–0)
Number
Added To
Byte
C After
DAA
0 9–0 0 0–9 00 0
0 0–8 0 A–F 06 0
0 0–9 1 0–3 06 0
ADD 0 A–F 0 0–9 60 1
ADC 0 9–F 0 A–F 66 1
INC 0 A–F 1 0–3 66 1
1 0–2 0 0–9 60 1
1 0–2 0 A–F 66 1
1 0–3 1 0–3 66 1
SUB 0 0–9 0 0–9 00 0
SBC 0 0–8 1 6–F FA 0
DEC 1 7–F 0 0–9 A0 1
NEG 1 6–7 1 6–F 9A 1
0 0 0 1 1 1 1 0 27