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Stack Pointer: Difference between revisions
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The '''Stack Pointer''' on the [[SPC700]] is 16-bit, but the upper byte is fixed by the hardware to be 0x01. | The '''Stack Pointer''' (SP) on the [[SPC700]] 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 are [[TCS]] and [[TXS]]. | On the [[65c816]], the only two instructions that modify the stack pointer (S) directly are [[TCS]] and [[TXS]].<sup>[4]</sup> 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. It points to the next available location on the stack. | |||
=== See Also === | |||
* [[TSX]] | |||
* [[TSC]] | |||
* [[PUSH]] | |||
* [[POP]] | |||
* [[RET]] | |||
* [[Program Counter]] | |||
=== References === | |||
# subparagraph 8.1.5 of [https://archive.org/details/SNESDevManual/book1/page/n182 page 3-8-4 of Book I] of the official Super Nintendo development manual | |||
# diversified activities: [https://archive.org/details/SNESDevManual/book1/page/n183 page 3-8-5 of Book I], lbid. | |||
# [[Eyes & Lichty]], [https://archive.org/details/0893037893ProgrammingThe65816/page/31 page 31] on The Stack Pointer | |||
# [[Eyes & Lichty]], [https://archive.org/details/0893037893ProgrammingThe65816/page/511 page 511] on TCS | |||
[[Category:ASM]] | [[Category:ASM]] | ||
[[Category:Registers]] | [[Category:Registers]] | ||
[[Category:Inherited from 6502]] | [[Category:Inherited from 6502]] | ||
Latest revision as of 15:28, 20 August 2024
The Stack Pointer (SP) on the SPC700 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. It points to the next available location on the stack.
See Also
References
- subparagraph 8.1.5 of page 3-8-4 of Book I of the official Super Nintendo development manual
- diversified activities: page 3-8-5 of Book I, lbid.
- Eyes & Lichty, page 31 on The Stack Pointer
- Eyes & Lichty, page 511 on TCS