RE: [stella] PAL TIM64T values

Subject: RE: [stella] PAL TIM64T values
From: "Lee Fastenau" <stella@xxxxxxxxxxxxxxx>
Date: Tue, 17 Aug 2004 01:00:14 -0500
> I'm trying to use TIM64T for easy T.V format conversions
> Here are the values I'm trying to use. The NTSC values
> work perfectly but the Kernel value for PAL is too high
> KERNEL = 228
>  TOTAL 262 lines
> KERNEL = 270
> OVERSCAN  = 42
>  TOTAL 312 lines
> Has anyone succesfully used this method?

Can I ask why you're using a timer for the display kernel?  I can only think
of two situations that would call for it:
	1. The game graphics only take up the upper portion of the screen, leaving
the remaining cycles in the bottom portion free for calculations and program
	2. The entire frame is used for lengthy calculations and program logic such
as in Maze Craze or Video Chess.

Outside of that, I would recommend manually counting scanlines in the
display kernel... but I'm still somewhat new to Stella coding myself, so
some of the veterans here might call me out on this. :)

When I built PAL support into my game, honestly, I tweaked the timer values
until Z26 displayed the correct number of scanlines.  I could have used the
formula in Nick Bensema's Guide to Cycle Counting, but this was pretty

Fortunately, I was able to narrow it down to a single working value, but
because the timer resolution is 64 cycles, it was certainly possible for two
consecutive values to work (both ending up in the correct 76-cycle
scanline).  If that had been the case, I would probably have used Nick's
formula to find the correct value.

So, basically, my answer is no, I've never used your method. :P


Current Thread