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Set Interrupt Disable Flag
Opcode: SEI
Operation: 1 → I
Status Register: Status-List.png

SEI (Set Interrupt Disable Flag) sets the Interrupt Flag in the Processor Status Register by setting the 2nd bit 1. To clear the interrupt disable flag, use CLI.


This pseudo C code shows how the SEI opcode functions when it is executed.

SET_INTERRUPT((1));           // Set the 2nd bit of the processor status to 1.

Addressing Modes

Addressing Mode Assembly Language Form Opcode # Bytes # Cycles
Implied SEI 78 1 2