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 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.

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
• NMI

Reference

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