Program Counter: Difference between revisions

Revision as of 21:55, 22 July 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.

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

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 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.
 On the [[S-SMP]] it is 16 bits wide.  The low byte is called PCL and the high byte is called PCH.
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 * 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
+* http://www.6502.org/tutorials/65c816opcodes.html#6.2.1.1
 [[Category:ASM]]
 [[Category:Registers]]
 [[Category:Inherited from 6502]]