dr.zeissler wrote:Ddave shows ugly strange textmode-characters when jumping.
Please stop using ambiguous abbreviations like that and just type the actual name of the game. Making me guess which game(s) you're talking about doesn't help anybody. There are four Dangerous Dave games for PC (five if you include the "Copyright Infringement" demo) and only two of them (Dave 3 and Dave 4) use the same graphic routines.
After reading the most recent posts above, I think I should mention that I don't understand half of the stuff you wrote. English isn't my first language and I'm probably not old or obsessed enough to know what "A2286/8" or "Q700" mean. Again, making me guess what you're talking about doesn't help.
I don't know anything about old EGA or VGA cards, I just know a bit about programing and assembly language. That's why I asked if you could name any games that can perform smooth scrolling correctly on your system. If you can't find a game that works correctly, then you're probably dealing with a hardware issue. Maybe some systems are too fast or too slow for the scrolling to work correctly. And when you're dealing with "ancient" hardware, there is also a chance that parts of the hardware have become faulty and that's why the games don't work correctly.
From what I've seen so far in the game's executables, there must have been some problems with the scrolling even back when Keen 4-6 were created. I found three different ways to handle timing for the panning just by looking at different versions of Keen 4. The source codes for Keen Dreams and Catacomb 3D contain a comment about someone's graphics card not accepting port output via word values (2 bytes at the same time). BioMenace still uses word-output, but all versions of Keen 4 that I've seen use byte-output, so the code must have been rewritten at some point to write each byte separately. Crystal Caves also uses word-output, but with yet another way (actually 2 other ways) to handle the timing.
My idea was to look at the code that works correctly on your system and then patch that code into the other games to make them work as well. If you can't find a game that works, then I can't help you.
Just to be clear: Jill of the Jungle, Duke Nukem 1, Cosmo's Cosmic Adventure, Word Rescue, Math Rescue, Dangerous Dave 1 (and many more) don't qualify. These games "scroll" the screen in multiples of 8 pixels, which doesn't require the panning feature at all. Games that do use panning are the entire Commander Keen series, Dangerous Dave 2-4, Rescue Rover 1+2, Crystal Caves, Secret Agent, BioMenace, Monster Bash, and Realms of Chaos. Yes, Realms of Chaos is a VGA game, but it still uses the panning feature to perform pixel-perfect scrolling.
Since the black screen issues with Crystal Caves and Secret Agent don't seem to appear in any other game, I have prepared a quick test for you. I found out that Crystal Caves switches to mode 10h (that's 640x350 pixels @ 16 colors) at startup, but the actual game runs in mode 0Dh (320x200 @ 16 colors). Maybe the change to mode 10h is what causes the black screen on your system. If it's not, then there's probably nothing else I can do about it (unless the original source code is released). I have hacked the executable for episode 1 of Crystal Caves so that it skips that video mode change. See attachment.