CHAPTER 3 CPU ARCHITECTURE
Preliminary User’s Manual U16315EJ1V0UD
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Figure 3-13. Format of Stack Pointer
15
0
SP
SP15 SP14 SP13 SP12 SP11 SP10 SP9
SP8
SP7
SP6
SP5
SP4
SP3
SP2
SP1
SP0
The SP is decremented ahead of write (save) to the stack memory and is incremented after read (restored) from
the stack memory.
Each stack operation saves/restores data as shown in Figures 3-14 and 3-15.
Caution Since RESET input makes the SP contents undefined, be sure to initialize the SP before
instruction execution.
Figure 3-14. Data to Be Saved to Stack Memory
Interrupt and
BRK instructions
PSW
PC15 to PC8
PC15 to PC8
PC7 to PC0
Register pair lower
SP SP _ 2
SP _ 2
Register pair upper
CALL, CALLF, and
CALLT instructions
PUSH rp instruction
SP _ 1
SP
SP SP _ 2
SP _ 2
SP _ 1
SP
PC7 to PC0
SP _ 3
SP _ 2
SP _ 1
SP
SP SP _ 3
Figure 3-15. Data to Be Restored from Stack Memory
RETI and RETB
instructions
PSW
PC15 to PC8
PC15 to PC8
PC7 to PC0
Register pair lower
SP SP + 2
SP
Register pair upper
RET instruction
POP rp instruction
SP + 1
PC7 to PC0
SP SP + 2
SP
SP + 1
SP + 2
SP
SP + 1
SP SP + 3