I can imagine that switching to and from mode 7 (or 135) from and to modes 0 to 6 (or 128 to 134) might cause some kind of resync, having vague memories of the way the Beeb's mode 7 sometimes appeared (it's been a long time, though), as well as the different video output paths involved.If I select the same mode twice in a row, will this cause this effect to happen twice, or does the fact the mode is the same mean the second one has no real effect on the monitor's hardware?
Between the same fundamental mode and its shadow companion, at least for the bitmap modes, I wouldn't expect any issues: they should effectively be the same 640 x 256 picture being generated continuously, obviously with mode-specific characteristics. Switching between mode 7 and 135 might conceivably retain the output signal, but you would have to dig a bit further to confirm that or otherwise.
Maybe someone can comment with more authority on the topic! I do remember some demo involving split screen modes incorporating mode 7, indicating that perhaps the SAA5050 can be made to cooperate with the video ULA.
Statistics: Posted by paulb — Mon Aug 26, 2024 8:58 pm