
Z80 Instruction Set UM008007-0715
116
Z80 CPU
User Manual
PUSH IY
Operation
(SP – 2) ← IYL, (SP – 1) ← IYH
Op Code
PUSH
Operand
IY
Description
The contents of Index Register IY are pushed to the external memory last-in, first-out
(LIFO) stack. The Stack Pointer (SP) Register pair holds the 16-bit address of the current
top of the Stack. This instruction first decrements the SP and loads the high-order byte of
IY to the memory address specified by SP; then decrements SP again and loads the low-
order byte to the memory location corresponding to this new address in SP.
Condition Bits Affected
None.
Example
If Index Register IY contains 2233h and the Stack Pointer contains 1007h, then upon the
execution of a PUSH IY instruction, memory address
1006h contains 22h, memory
address
1005h contains 33h, and the Stack Pointer contains 1005h.
M Cycles T States 4 MHz E.T.
4 15 (4, 5, 3, 3) 3.75
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