Interrupt Disable Flag

The Interrupt Disable Flag (I) exists on the 65c816 as bit 2 of the status register.

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

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

BRK ignores it.

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