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 2stolber@xxxxxxxxxxxxxxxxxxxxxxxxx
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