ZiLOG eZ80

eZ80
®
CPU
User Manual
UM007714-0908 CPU Instruction Set
282
PUSH AF
Push Stack
Operation
if ADL mode {
(SPL – 1) ← 00h
(SPL – 2) ← A
(SPL – 3) ← F
SPL ← SPL – 3
}
else Z80 mode {
(SPS – 1) ← A
(SPS – 2) ← F
SPS ← SPS – 2
}
Description
In ADL mode, or when the .L suffix is employed, 3 bytes are pushed onto the memory
locations indicated by SPL, in the following sequence:
1. A value of
00h is written to the memory location with address SPL – 1.
2. The CPU writes the contents of the accumulator, A, to the memory location with
address SPL
– 2.
3. The CPU next writes the contents of the Flags Register, F, to the memory location
with address SPL
– 3.
SPL decrements by three.
In Z80 mode, or when the
.S suffix is employed, 2 bytes are pushed onto the memory loca-
tions indicated by SPS, in the following sequence:
1. The CPU writes the contents of the accumulator, A, to the memory location with
address SPS
– 1.
2. The CPU next writes the contents of the Flags Register, F, to the memory location
with address SPS
– 2.
SPS decrements by two.
Condition Bits Affected
None.