BUGS.TXT

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Known bugs in pdpapl
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=== System clock lag ===

pdpapl takes over complete control of the Line Time Clock during its
run, which has the side effect of offsetting RT-11's system clock
by exactly the program's execution time; this necessitates the manual
setting of the system clock post-execution.

If you have any idea how RT-11 works (I don't), please do submit a
pull request, or send me the relevant part of a manual on interrupts.

=== Latency in KWRTNE ===

If the drawing of a single frame and setting of PFWAIT takes longer
than the time between two executions of the `BICB #PFWAIT,PFLAGS' line
in the KWRTNE subroutine, the drawing of the frame after said frame
will be delayed till the next execution of said line.

Explained visually:

Draw time	|--- 0 ---|  |------- 1 -------|       |---- 2 ---| |--
FPSLEN		|------------|------------|------------|------------|--
PFWAIT set?	..........***..................********...........**...

Despite its inclusion in this file, this is intentional design.
I'd rather have a video that's on the beat and behind one or two frames
than a video that's somewhat close to on-time but off-beat.