Zilog Z08470 - Manual (Page 128)

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
1 1 1 0 1 1 1 1 FD
1 1 0 0 1 1 1 0 E5