Posted By
SukkoPera
on 2025-09-15
09:09:42
|  Jiffy count/Jiffies broken on PAL JiffyDOS
Apparently I have found out that the PAL version of JiffyDOS does not properly compensate the "jiffy count" ($a3/$a4/$a5) for 50 Hz.
The original KERNAL code contains a hack that wedges in an extra tick every 5, so that the jiffy clock can still (irregularly) tick 60 times per second (as on NTSC systems) even when the system is running at 50 Hz (PAL frequency).
The PAL version of JiffyDOS does not seem to contain the hack, thus the jiffy clock only ticks 50 times per second on PAL systems.
The KERNAL itself does not seem to use the jiffy counter in any way, so I'm curious if anyone is aware of anything else that uses it and whether that gets broken in any way with JiffyDOS. Also, since I already have a patch for the problem, I'd like to use such software to test it  .
Any suggestions?
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