WAI: Difference between revisions

Revision as of 13:38, 14 December 2023


Basic Info
Addressing Mode	Opcode	Length	Speed
Implied (type 3)	CB	1 byte	3 cycles


Flags Affected
N	V	M	X	D	I	Z	C
.	.	.	.	.	.	.	.

WAI (WAit for Interrupt) is a 65x instruction that waits until an interrupt is received. The processor consumes less power while waiting. The RDY pin is pulled low during the third cycle. The interrupt is serviced immediately.

If the interrupt disable flag is set, then the way servicing occurs is for control to simply fall through to the instruction following WAI.

If that flag clear, control instead goes into the interrupt handler.

External Links

Eyes & Lichty page 522, on WAI: https://archive.org/details/0893037893ProgrammingThe65816/page/n548
Labiak page 203 on WAI: https://archive.org/details/Programming_the_65816/page/n213
snes9x implementation of WAI: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L3313
undisbeliever on WAI: https://undisbeliever.net/snesdev/65816-opcodes.html#wai-wait-for-interrupt

@@ Line 36: / Line 36: @@
 '''WAI''' (WAit for Interrupt) is a 65x instruction that waits until an interrupt is received.  The processor consumes less power while waiting.  The [[RDY pin]] is pulled low during the third cycle.  The interrupt is serviced immediately.
+If the [[interrupt disable flag]] is set, then the way servicing occurs is for control to simply fall through to the instruction following WAI.
+If that flag clear, control instead goes into the [[interrupt handler]].
 === See Also ===