ZiLOG eZ80

eZ80
®
CPU
User Manual
UM007714-0908 CPU Instruction Set
324
RRD
Rotate Right Decimal
Operation
A[3:0] ← HL[3:0]
HL[7:4] ← A[3:0]
HL[3:0] ← HL[7:4]
Description
The CPU copies the contents of the low-order four bits of the memory location (HL) into
the low-order four bits of the accumulator, A. The CPU next copies the previous contents
of the low-order four bits of the accumulator into the high-order four bits of (HL). The
CPU next copies the previous contents of the high-order four bits of (HL) into the low-
order four bits of (HL).
Condition Bits Affected
Attributes
S Set if the accumulator is negative; reset otherwise.
Z Set if the accumulator is 0; reset otherwise.
H Reset.
P/V Set if parity of the accumulator is even; reset otherwise.
N Reset.
C Not affected.
Mnemonic Operand ADL Mode Cycle Opcode (hex)
RRD —X 5ED, 67
3
7
4
0
3
7
4
0
(HL)
A