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Accumulator: Difference between revisions
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The [[65c816]]'s accumulator can be either 8 or 16 bits in size, as configured by the M flag. Labiak calls this 16-bit memory mode. | The [[65c816]]'s accumulator can be either 8 or 16 bits in size, as configured by the M flag. Labiak calls this 16-bit memory mode. | ||
The high byte ("B") is still retained even when the accumulator is 8 bits wide. | The high byte ("B") is still retained even when the accumulator is 8 bits wide and can be accessed with [[XBA]]. | ||
The [[S-SMP]]'s accumulator is always 8 bits wide. | The [[S-SMP]]'s accumulator is always 8 bits wide. | ||
Revision as of 14:21, 24 July 2024
An Accumulator is a very fast register inside a processor that acts as a mathematical scratch pad.
The 65c816's accumulator can be either 8 or 16 bits in size, as configured by the M flag. Labiak calls this 16-bit memory mode.
The high byte ("B") is still retained even when the accumulator is 8 bits wide and can be accessed with XBA.
The S-SMP's accumulator is always 8 bits wide.
See Also
References
- Eyes & Lichty page 27, https://archive.org/details/0893037893ProgrammingThe65816/page/27
- subparagraph 8.1.1 A Register on page 3-8-4 of Book II of the official Super Nintendo development manual