[stella] comments on Matt's programs

Subject: [stella] comments on Matt's programs
From: Eckhard_Stolberg@xxxxxxxxxxxxxxxxxxxxx (Eckhard Stolberg)
Date: Sun, 13 Oct 1996 22:16:01 +0200
Hello matt,

I have just tested your programs and I think you are not doing the timing
right. Your programs only wait for 320 cycles for the overscan and for the
vblank as well. That is just enough for 5 lines of waiting for each of them.

The stella programmer's guide says, that a propper NTSC TV frame consists of
  3 lines vsync
 37 lines vblank
192 lines graphics and
 30 lines overscan.

A PAL TV frame should have
  3 lines vsync
 45 lines vblank
228 lines graphics and
 36 lines overscan.

While the number of lines for the graphics can be smaller, it is important,
that the number of lines for everything else are exactly right. Otherwise
you get a rolling picture and wrong colours.

That is, what I got, when I tried out your ROMs. But after I changed the 
values for the Tim64t timer and reassembled the sourcecode, your programs
worked on my system. Although I only have a PAL system, I think your original
ROMs wouldn't work on NTSC systems either.

Ciao, Eckhard Stolberg

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