Whenever the CPU is busy, the power led goes on else it is off. It operates
using timerA on CIAB. This is continuosly 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 2.1a add new features. Include C source, Author: Lindsay Meek