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Break Flag: Difference between revisions

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The '''Break Flag''' (B) exists on the [[SPC700]], as bit 4 of the [[Program Status Word]]It discerns between [[IRQ]]s and [[BRK]].
Note: This page may be confusing or inaccurateSee the talk page.


BRK and [[PHP]] set the break flag.  IRQs and [[NMI]]s clear it. <sup>[1]</sup>
The '''Break Flag''' (B) is bit 4 of the [[S-SMP]]'s [[program status word]].  It discerns between [[IRQ]]s and [[BRK]].
 
BRK and [[PHP]]<sup>[dubious]</sup> set the break flag.  IRQs, [[NMI]]s, and reset clear it.<sup>[1]</sup>
 
[[RETI]] and [[POP]] can modify the break flag.
 
In [[emulation mode]] the [[65c816]] has a break flag too.<sup>[2]</sup>  But in native mode it becomes the [[Index Register Select]].  [[PLP]] can affect the break flag.<sup>[3]</sup>
 
=== See Also ===
* [[B Flag (Super FX)]]
 
=== References ===
# https://problemkaputt.de/fullsnes.htm#cpuregistersandflags
# [[Eyes & Lichty]], [https://archive.org/details/0893037893ProgrammingThe65816/page/422 page 422], Table 18.2. 65x Flags.
# [https://archive.org/details/0893037893ProgrammingThe65816/page/486 page 486], lbid.
# Fragment 18.1 on [https://archive.org/details/0893037893ProgrammingThe65816/page/436 page 436] on BRK, lbid.


[[Category:ASM]]
[[Category:ASM]]
[[Category:SPC700]]
[[Category:SPC700]]
[[Category:Flags]]
[[Category:Flags]]
 
[[Category:Inherited from 6502]]
=== References ===
[[Category:Condition Codes]]
# https://problemkaputt.de/fullsnes.htm#cpuregistersandflags

Latest revision as of 22:21, 21 August 2024

Note: This page may be confusing or inaccurate. See the talk page.

The Break Flag (B) is bit 4 of the S-SMP's program status word. It discerns between IRQs and BRK.

BRK and PHP[dubious] set the break flag. IRQs, NMIs, and reset clear it.[1]

RETI and POP can modify the break flag.

In emulation mode the 65c816 has a break flag too.[2] But in native mode it becomes the Index Register Select. PLP can affect the break flag.[3]

See Also

References

  1. https://problemkaputt.de/fullsnes.htm#cpuregistersandflags
  2. Eyes & Lichty, page 422, Table 18.2. 65x Flags.
  3. page 486, lbid.
  4. Fragment 18.1 on page 436 on BRK, lbid.