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Pop iy – Zilog Z08470 User Manual

Page 132

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Z80 Instruction Set

UM008007-0715

120

Z80 CPU
User Manual

POP IY

Operation

IYH ← (SP – X1), IYL ← (SP)

Op Code

POP

Operand

IY

Description

The top two bytes of the external memory last-in, first-out (LIFO) stack are popped to
Index Register IY. The Stack Pointer (SP) Register pair holds the 16-bit address of the cur-
rent top of the Stack. This instruction first loads to the low-order portion of IY the byte at
the memory location corresponding to the contents of SP; then SP is incremented and the
contents of the corresponding adjacent memory location are loaded to the high-order por-
tion of IY. The SP is incremented again.

Condition Bits Affected

None.

Example

If the Stack Pointer Contains

1000h

, memory location

1000h

contains

55h

, and location

1001h

contains

33h

, the instruction POP IY results in Index Register IY containing

3355h

, and the Stack Pointer containing

1002h

.

M Cycles

T States

4 MHz E.T.

4

14 (4, 4, 3, 3)

3.50

1

1

1

0

1

1

0

1

DD

1

1

1

0

1

1

1

1

FD

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