|16h||DP$WRDY||wait on a timed semaphore|
|Input||- none -|
|Output||- none -|
Waits until the value in dpw_redy has been decremented to 0.
Each keyboard interrupt causes dpw_redy to be decremented by 1 and as such provides a handy 50 millisecond timer. However if interrupts are switched off this routine will still work as it recognises that interrupts are off and decrements dpw_redy once every 50 milliseconds.
Note that this routine behaves as a wait on a timed semaphore. It is used extensively by the LCD driver software to provide scrolling delays.
The following routine waits for 3 seconds
LDD #60 STD DPW_REDY OS DP$WRDY RTS
|Errors||- none -|