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CHAPTER 4 INTERNAL CPU FUNCTIONS
Figure 4-11. Format of Stack Pointer and Stack Bank Select RegisterNote The Mk I mode and Mk II mode can be switched by bit 3 of SBS. The stack bank selection functioncan be used in both Mk I mode and Mk II mode. (See Section 4.1 for details.)Example SP initializationSpecify memory bank 1 as a stack area to start stack operation at address 1FFH.SEL MB15 ; or CLR1 MBEMOV A,#1MOV SBS,A ; Specify memory bank 1 as a stack areaMOV XA,#00HMOV SP,XA ; SP <– 00HFigure 4-12. Data Saved to the Stack Memory (Mk I Mode)Note PC12 and PC13 are 0 in the µPD750004. PC13 is 0 in the µPD750006 and µPD750008.
SP
SP
SP7 SP6 SP5 SP4 SP3 SP2 SP1 0
SBS0
SBS10
SBS3
SP
SBS
Symbol
F80H
F84H
Address
SBS
0FFH
100H
000H
1FFH
Memory bank 0
Memory bank 1
Note
SP – 6 PC11 - PC8
MBE
SP – 4 PC3 - PC0
PC7 - PC4
SP – 2 IST1
CY
SP – 5
SP – 3
SP – 1
Stack
RBE
PC12
IST0
SK2
MBE
SK1
RBE
SK0
Interrupt
PSW
SP – 4 PC11 - PC8
MBE
SP – 2 PC3 - PC0
PC7 - PC4
SP – 3
SP – 1
Stack
RBE
PC13 PC12
CALL or CALLF instruction
SP – 2
Lower bits of pair register
Upper bits of pair register
SP
SP – 1
Stack
PUSH instruction
Note
SP
SP
Note
PC13
Note Note