Marius Posted October 3, 2014 Share Posted October 3, 2014 Hi In the Hobby Tronic Demo 1991 there is the 2nd part from Peter Sabath. It is a nice demo. But most times it does not run here. I added an ATR here with HS loader where you can separately load the demo's. On the original Hobby Tronic demo disk is the same problem, so it is not the problem with High Speed Loader or a problem with this conversion. I hope someone can fix this demo. Or tell me what the issue is why it crashes. As soon as you see the 'depacking' (3 phases) the demo will crash as soon as it runs (sometimes it does run, but then the graphics are disturbed). Strange enough: when the demo is loaded and the screen is full of garbage (so you do not see the depacking sequence) THEN it runs properly! Anyone? Thanks a lot Marius Quote Link to comment Share on other sites More sharing options...
Madi Posted October 3, 2014 Share Posted October 3, 2014 Great Demo. Thank you I ran the demo (A-E) several times without noticing any discrepancies. It runs great on PAL system. When I run it under NTSC, I get all that weird sound and off graphics stuff. (Under Altirra emulator) madi Quote Link to comment Share on other sites More sharing options...
+CharlieChaplin Posted October 3, 2014 Share Posted October 3, 2014 Hello Marius, I know exactly what you mean, but do not know why the demo behaves like this. Besides the official Abbuc version there is also a version by TOP-Magazin with single-parts one can choose from. But it has nearly the same problems as the Abbuc version (except one can choose the Peter Sabath megaballs-demo without watching the other parts first). When the demo depacks, there are two behaviours: a) you see garbage while depacking and think the demo will crash, but surprisingly it then works alright, b) you do not see garbage while depacking and think the demo will work, but surprisingly it crashes. Maybe some Atari expert (JAC? anybody else) can find out whats wrong here or why the demo sometimes works and somtimes does not... Last not least, afaik you have a 4MB cart from Bernd/santosp - there is a ROM version with demos available at Abbuc forum by yellowman which also contains a single-file version of the megaballs demo. This versions seems to work for me (someone put the XEX/COM file on a shortened ATR-image created with MakeATR by Ken Siders). Think it is possible to extract the ATR image from the cart (the ROM) and turn it back into a XEX/COM file again (with UnmakATR also by Ken Siders)... 1 Quote Link to comment Share on other sites More sharing options...
bfollett Posted October 3, 2014 Share Posted October 3, 2014 (edited) Just a guess, is the demo just doing too many things in display list interrupts. You don't have as many cycles available in NTSC as PAL. There are plenty of programs that don't behave well on NTSC because of that. Bob Edited October 3, 2014 by bfollett Quote Link to comment Share on other sites More sharing options...
Mathy Posted October 3, 2014 Share Posted October 3, 2014 Hello guys IIRC Peter Sabath visited the annual meetings of the ABBUC at least once in the last couple of years. That would mean that he's not vanished from the world completely. Maybe somebody in the ABBUC knows where he can be found. Sincelery Mathy Quote Link to comment Share on other sites More sharing options...
+CharlieChaplin Posted October 3, 2014 Share Posted October 3, 2014 (edited) Just a guess, is the demo just doing too many things in display list interrupts. You don't have as many cycles available in NTSC as PAL. There are plenty of programs that don't behave well on NTSC because of that. Bob But errm, since Marius and me are both from Europe (Netherlands, Germany) we do have PAL Ataris, so this is not the problem here. Peter Sabath (the author of this demo) is from Germany, he programmed the demo on a PAL Atari and still it does not run on every PAL Atari. Furthermore on one and the same PAL Atari with always the same disk (and the same version) this demo sometimes runs perfect and sometimes does not run at all... strange, eh...?!? Edited October 3, 2014 by CharlieChaplin 1 Quote Link to comment Share on other sites More sharing options...
phaeron Posted October 4, 2014 Share Posted October 4, 2014 Instability is due to unsafe display list switching -- the demo overwrites the active display list, changes the shadow display list pointer (SDLSTL/SDLSTH), and then turns on display list interrupts. ANTIC runs garbage as the display list for the end of the current frame, and the random DLIs can toast the demo, particularly if the stack wraps. 3 Quote Link to comment Share on other sites More sharing options...
Marius Posted October 4, 2014 Author Share Posted October 4, 2014 Since the demo is packed, I guess it is harder to fix it... Perhaps a solution would be to make some kind of 'savestate' just after the depacking is finished, do a SEI and then do a JMP run-address? @CharlieChaplin: Thanks for your detailed response. I am going to take a look at that demopackage for megacart. Sounds cool anyway, i LOVE demo's! Quote Link to comment Share on other sites More sharing options...
Heaven/TQA Posted October 4, 2014 Share Posted October 4, 2014 And that from an A8 pro coder... we are all humans Quote Link to comment Share on other sites More sharing options...
Marius Posted October 4, 2014 Author Share Posted October 4, 2014 Well it probably happened this way: Peter Sabath finished his demo without the packing sequence. Everything worked fine. He packed the stuff, and probably tested it once, and that moment it did work. Perhaps a rush job, and sent in for the Hobby Tronic disk. Couldn't find any other explanation. Quote Link to comment Share on other sites More sharing options...
Mclaneinc Posted October 5, 2014 Share Posted October 5, 2014 Crashes all over the place for me, I also notice it crashes if start is pressed in the bits that do work but I presume that's because in the working version I have, start loads the next part. Quote Link to comment Share on other sites More sharing options...
Marius Posted October 5, 2014 Author Share Posted October 5, 2014 Crashes all over the place for me, I also notice it crashes if start is pressed in the bits that do work but I presume that's because in the working version I have, start loads the next part. That is true. It was originally part of Side A of the Hobby Tronic 1991 demo disk. This is an extract. Pressing start (or waiting long enough, when the demo runs) will move to the other part in the original disk, but on this disk it means crash. That's normal behavior Quote Link to comment Share on other sites More sharing options...
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