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PSHY
(SP) – $0002 ⇒ SP
Operation:
(Y
H
Description:
Stacks the content of index register Y. The stack pointer is decremented
by two. The content of Y is then stacked at the address to which the SP
points. After PSHY executes, the SP points to the stacked value of the
high-order half of Y.
Push instructions are commonly used to save the contents of one or
more CPU registers at the start of a subroutine. Complementary pull in-
structions can be used to restore the saved CPU registers just before re-
turning from the subroutine.
Condition Codes and Boolean Formulas:
S
–
None affected.
Addressing Modes, Machine Code, and Execution Times:
Source Form
PSHY
CPU12
REFERENCE MANUAL
Push Index Register Y onto Stack
) ⇒ M
: Y
: M
(SP + 1)
L
(SP)
X
H
I
N
Z
–
–
–
–
–
Address Mode
INH
INSTRUCTION GLOSSARY
V
C
–
–
Object Code
35
PSHY
Cycles
Access Detail
2
OS
MOTOROLA
6-159
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