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| [65] Effects of 'SLO', 'RLA', etc, etc http://forum.6502.org/viewtopic.php?f=7&t=322 |
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| Author: | ThomasHarte [ Fri Sep 01, 2000 4:37 pm ] |
| Post subject: | [65.1] Effects of 'SLO', 'RLA', etc, etc |
Even 64doc just skims over this, so I'm wondering - for SLO (opcodes like &2f which produce an ORA and an ASL at once) and RLA (ROL + AND), exactly what are the results? A value is read from memory, and written back to it, and at some point the two operations occur, but with SLO for example, is the value shifted before it is or'd, or not? Is the write back just the shifted value, or is it the shifted value after the or - i.e. exactly the value found in the accumulator? And how are the flags set? Thanks in advance! |
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