Turns the power LED off when the CPU is idle. It operates using timerA on CIAB. This is continuously reset by the idle task running at low priority (-127). When the idle task is preempted by anything, the timer is allowed to underflow causing the interrupt server to run which turns on the power light. Next time the idle task runs, it immediately turns off the power light. Version 1.0a, includes source. Author: Lindsay Meek