UPD17134A Datasheet, PDF (256/292 Pages) NEC – 4-BIT SINGLE-CHIP MICROCONTROLLER

CHAPTER 19 INSTRUCTION SET
(8) POP AR
<1> OP code
00111
000
1100
0000
<2> Function
AR ← ASR,
SP ← SP + 1
Pop address register
1
2
3
4
5
Pops the contents of address stack register indicated by stack pointer to address register AR and then
6
increments stack pointer SP.
<3> Example
7
If the PSW contents are changed, while an interrupt processing routine is being executed, the PSW
8
contents are transferred to the address register through WR at the beginning of the interrupt processing
and saved to address stack register by the PUSH instruction. Before the execution returns from the
9
interrupt routine, the address register contents are restored through WR to PSW by the POP instruction.
10
Interrupt processing routine
11
PEEK
WR, PSW
POKE AR0, WR
EI
PUSH AR
12
13
Generates
interrupt source
14
15
POP
AR
16
PEEK
WR, AR0
POKE PSW, WR
RET (or RETI)
17
18
19
20
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