FYI

    SM 0 a9f4 writes a9 f4 into memory at address 0
    G 0 starts executing at address 0

    A9F4 is the ExitToShell A-trap, which terminates the
    current process.

With those commands you could terminate the foreground task on System 7 and were (usually) given a chance to save or recover something before rebooting.

It could also be used to kill At Ease on most school setups.