Zilog Z08470 - Manual (Page 125)

UM008007-0715 Z80 Instruction Description
Z80 CPU
User Manual
113
PUSH qq
Operation
(SP – 2) ← qqL, (SP – 1) ← qqH
Op Code
PUSH
Operand
qq
Description
The contents of the register pair qq 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 SP and loads the high-order byte of reg-
ister pair qq to the memory address specified by the SP. The SP is decremented again and
loads the low-order byte of qq to the memory location corresponding to this new address
in the SP. The operand qq identifies register pair BC, DE, HL, or AF, assembled as follows
in the object code:
Condition Bits Affected
None.
Pair qq
BC 00
DE 01
HL 10
AF 11
M Cycles T States 4 MHz E.T.
3 11 (5, 3, 3) 2.75
1 1 q 0 1 1 q 0