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SEP

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Revision as of 21:22, 3 August 2024 by Xetheria (talk | contribs) (why SEP can't modify m/x in emulation mode)
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Basic Info
Addressing Mode Opcode Length Speed
Immediate E2 2 bytes 3 cycles
Flags Affected
N V M X D I Z C
emulation mode N V . . D I Z C
native mode N V M X D I Z C

SEP (Set Status Bits) is a 65c816 instruction that sets bits in the status register that correspond to set bits in the operand.

SEP is the only way to set the m and x flags directly (but PLP and RTI may set them too.)[1] But, SEP can't modify those two flags in emulation mode because they are being forced to be set.

Syntax

SEP #nvmxdizc

See Also

References

  1. Eyes & Lichty page 502, on SEP: https://archive.org/details/0893037893ProgrammingThe65816/page/502
  2. Labiak page 183 on SEP: https://archive.org/details/Programming_the_65816/page/n193
  3. snes9x implementation of SEP: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L3203
  4. undisbeliever on SEP: https://undisbeliever.net/snesdev/65816-opcodes.html#sep-set-status-bits