We've just updated MediaWiki and its underlying software. If anything doesn't look or work quite right, please mention it to us. --RanAS

Program Counter: Difference between revisions

From SnesLab
Jump to: navigation, search
(no penalty in native mode)
(→‎References: hid archive URL for E&L)
Line 13: Line 13:


=== References ===
=== References ===
* [[Eyes & Lichty]] page 33, https://archive.org/details/0893037893ProgrammingThe65816/page/33
* [[Eyes & Lichty]], [https://archive.org/details/0893037893ProgrammingThe65816/page/33 page 33]
* subparagraph 8.1.4 on [https://archive.org/details/SNESDevManual/book1/page/n182 page 3-8-4 of Book I] of the official Super Nintendo development manual
* subparagraph 8.1.4 on [https://archive.org/details/SNESDevManual/book1/page/n182 page 3-8-4 of Book I] of the official Super Nintendo development manual
* Pickens, John. http://www.6502.org/tutorials/6502opcodes.html#PC
* Pickens, John. http://www.6502.org/tutorials/6502opcodes.html#PC

Revision as of 19:36, 8 August 2024

The Program Counter (PC) keeps track of which instruction is currently executing. If incremented past FFFFh, it wraps around to zero.

The 6502 had 16-bit absolute addressing but only an 8-bit adder, so in emulation mode branches that cross a page boundary incur a one cycle penalty. 65c816 native mode has no such penalty because the full 16-bit adder is used.

On the S-SMP it is 16 bits wide. The low byte is called PCL and the high byte is called PCH.

See Also

References