46h KB$BREK test ON/CLEAR key
Input - none -
Output Carry flag is set if ON/CLEAR key is pressed.

Tests if ON/CLEAR key is pressed.

The key is tested for directly by reading PORT 5 and then searched for in the keyboard buffer KBT_BUFF. If ON/CLEAR is detected, KB$BREK waits for it to be released, then flushes the keyboard buffer and returns the carry flag set. If no ON/CLEAR key is found, the carry flag is cleared.

Errors - none -