Stack Pointer

The Stack Pointer (SP) points to the next stack location available for pushing to. On the SPC700 it is 16-bit, but the upper byte is fixed by the hardware to be 0x01.

On the 65c816, the only two instructions that modify the stack pointer (S) directly are TCS and TXS.^[4] It is only fixed to be in page one in emulation mode on the '816.

1FFh is a common value to initialize the stack pointer to.

Pushing things onto the stack decrements the stack pointer and pulling things increments it.

See Also

• TSX
• TSC
• PUSH
• POP
• RET
• Program Counter

References

1. subparagraph 8.1.5 of page 3-8-4 of Book I of the official Super Nintendo development manual
2. diversified activities: page 3-8-5 of Book I, lbid.
3. Eyes & Lichty, page 31 on The Stack Pointer
4. Eyes & Lichty, page 511 on TCS