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Memory/Accumulator Select: Difference between revisions

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(does not affect TCS)
(does not affect TCS)
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* [[TRB]]
* [[TRB]]


But it does not affect [[XBA]], [[TDC]], [[TCD]], or [[TCS]].
But it does not affect [[XBA]], [[TDC]], [[TCD]], [[TCS]], or [[TSC]].


There are no BMS or BMC instructions that examine this flag.
There are no BMS or BMC instructions that examine this flag.

Revision as of 17:39, 16 August 2024

The Memory/Accumulator Select (M) flag is bit 5 of the 65c816's processor status register. It indicates whether the accumulator is 8 or 16 bits wide:

  • When clear, the accumulator is 16 bits wide. It can only be clear in native mode.
  • When set, the accumulator is 8 bits wide, but the high byte (B) is still retained. This is the case after reset because the processor is in emulation mode.

It can be affected by:

It affects the behavior of (possibly incomplete list):

But it does not affect XBA, TDC, TCD, TCS, or TSC.

There are no BMS or BMC instructions that examine this flag.

See Also

Reference