Break Flag: Difference between revisions

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]

@@ Line 1: / Line 1: @@
-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 inaccurate.  See 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:SPC700]]
 [[Category:Flags]]
+[[Category:Inherited from 6502]]
-=== References ===
+[[Category:Condition Codes]]
-# https://problemkaputt.de/fullsnes.htm#cpuregistersandflags