Z8
®
CPU
User Manual
UM001604-0108 Instruction Description
215
PUSH
Syntax
PUSH src
Instruction Format
Operation
SP ← SP–1
@SP ← src
The contents of the SP (stack pointer) are decremented by one, then the contents of the
source operand are loaded into the location addressed by the decremented SP, thus adding
a new element to the stack.
Address modes R or IR can be used to specify a 4-bit Working Register. In this format, the
destination Working Register operand is specified by adding
1110b (Eh) to the high nibble
of the operand. For example, if Working Register R12 (CH) is the destination operand, then
ECh is used as the destination operand in the Op Code.
Example 1
If the SP contains 1001h, the statement:
PUSH FCh
Op Code: 70 FC
stores the contents of Register FCh (the Flag Register) in location 1000h. After the PUSH
operation, the SP contains
1000h.
Cycles
OPC
(Hex)
Address Mode
dst
10 Internal Stack 70
OPC src
12 External Stack R
10 Internal Stack IR
10 External Stack 71
Flag Description
C Unaffected
Z Unaffected
S Unaffected
V Unaffected
D Unaffected
H Unaffected
Edst
Note:
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