STP - Stop Processor

Stop the Processor until Reset

STP will stop the processors oscillator input, shutting down the processor until a reset occurs by pulling the RES pin low.

As power consumption is a function of frequency in CMOS circuits, stopping the clock cuts power to almost nothing.

Flags Affected
SyntaxOpcode Available on: # of # of Addressing Mode
(hex) 6502 65C02 65816 bytes cycles
STP DB x 1 31 Implied


  1. Uses 3 cycles to shut down the processor. Additional cycles required by reset to restart it

Last modified November 5, 2021: Add instruction categories (6b74ff9)