Interrupt Disable Flag

The Interrupt Disable Flag (I) is bit 2 of the 65c816's status register.

SEI sets it and CLI clears it. (SEP and REP can affect it as well.) BRK and COP set it too.

This flag is automatically set whenever the processor begins servicing an interrupt.

BRK ignores its previous state. NMIs generated by the vertical blanking period also cannot be ignored.

There are no BIS or BIC instructions that examine this flag (though there is an unrelated BIC (Super FX) instruction).

See Also

• Interrupt Enable Flag
• IRQ
• WAI

Reference

• Pickens, John. NMOS 6502 Opcodes. http://www.6502.org/tutorials/6502opcodes.html#IFLAG