Rybags Posted October 31, 2017 Share Posted October 31, 2017 I'd forgotten about that one. Actually the one I was thinking about has Santa Claus and a snowy backdrop. Didn't get anywhere near the detail I wanted in the pic, from memory it was a quick & dirty Photoshop job. Found it, on the NYD2009 disk... press Space to stop the screen jitter. NYD2k9.atr 1 Quote Link to comment Share on other sites More sharing options...
popmilo Posted October 31, 2017 Share Posted October 31, 2017 Erp... has someone figured out 80 column text output? (This is giving me a Centron flashback.) What do you mean by that ? Quote Link to comment Share on other sites More sharing options...
Rybags Posted November 1, 2017 Share Posted November 1, 2017 Seems I was mistaken in my description of what I did with those two demos (NY 2009 & 2010). It's a mix of GTIA colour (80 pixel res) in bitmap with the character line providing luma at 160 pixel resolution, result being 16 * 6 = 96 colours with restrictions. Of course, there's no reason why VScrol tricks can't be used with Antic 4 to produce shorter characters with the intention of giving more PF2/3 attribute options. 1 Quote Link to comment Share on other sites More sharing options...
fox Posted November 6, 2017 Author Share Posted November 6, 2017 Erp... has someone figured out 80 column text output?If Phaeron is right about AND or OR done on character data, we aren't going to get hardware 80-character mode. Otherwise, it looks possible! (with 4x8 font) 1 Quote Link to comment Share on other sites More sharing options...
kenjennings Posted November 9, 2017 Share Posted November 9, 2017 (with 4x8 font) This has already been done. In fact, a long time ago, back in the 80s. Quote Link to comment Share on other sites More sharing options...
phaeron Posted November 9, 2017 Share Posted November 9, 2017 This has already been done. In fact, a long time ago, back in the 80s. Not that I'm aware of. He's talking about a mode where ANTIC is still doing the character data lookup, which it can't do directly because it doesn't have enough on-chip buffer for 80 characters. You might be thinking of alternate-frame flickering between even/odd chars or doing software rendering of characters to a bitmap screen, which aren't what he's suggesting. Quote Link to comment Share on other sites More sharing options...
fox Posted November 9, 2017 Author Share Posted November 9, 2017 it can't do directly because it doesn't have enough on-chip buffer for 80 charactersAh yes. Even with one scanline high characters using VSCROL and switching the font every scanline, it's not going to work because same data goes to character names and font. We see four bits of the font, that limits us to just 16 different characters. And there's an AND on the address bus. 1 Quote Link to comment Share on other sites More sharing options...
Rybags Posted November 9, 2017 Share Posted November 9, 2017 There is a simulated 640 mode where they alternate background colour. Just whether the phase shift of colour also generates the required pixel delay... I have real doubts. Back to reality... in theory if you did 480i interlace with the monitor on it's side, that gives you 60 columns. Or 80 columns if using 6 pixel across characters. 1 Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted November 9, 2017 Share Posted November 9, 2017 why can't the name be the character data and vice versa.... the computer isn't a person.. it doesn't care and we would as people just need to recognize the data pattern.... Mr. Robot... Quote Link to comment Share on other sites More sharing options...
ijor Posted November 10, 2017 Share Posted November 10, 2017 In my (very long) TODO list is to provide an Antic simulation model so that this sort of stuff could be "easily" tested. Easily assuming you are more or less familiar with simulation models. 2 Quote Link to comment Share on other sites More sharing options...
phaeron Posted November 10, 2017 Share Posted November 10, 2017 Well, vector math says that you can get a true phase shift from adding color... but the only way to get a true 90 degree shift out of the result is to have the chroma signal be stronger than the luma signal. That's going to be a pretty dim result given how low the brightness would need to be. With regard to trying an HSCROL hack: I realized that overlap of name/data fetch is one thing, but the overlap of the display list fetch might be more troublesome. The HSCROL trick will leave half of the bits in the DMA clock for 1 fetch / 2 cycles, but character mode will project this onto both even and odd cycles. This means that the display list fetch will be impacted, and I believe this will be a three-way conflict between DL fetch, name fetch, and data fetch. Worse, the data fetch will be driven by a name fetch three cycles earlier in the region where playfield DMA is blocked, meaning that it'll pick up bus data from the 6502 instead. Can't dodge this by disabling DMACTL bit 5 as display list DMA is the only way to toggle the vertical scrolling bit to shorten the mode lines. It's possible to get all of these to line up to produce the desired address, but it'd be tricky. One way might be to just force the combined address to $0000 and toggle that address for the desired display list byte. 2 Quote Link to comment Share on other sites More sharing options...
Rybags Posted November 12, 2017 Share Posted November 12, 2017 For what it's worth you can repeat mode by disabling DList fetch but that's not any use if you're wanting to use VScrol tricks for shorter characters. Quote Link to comment Share on other sites More sharing options...
fox Posted November 21, 2017 Author Share Posted November 21, 2017 I believe this will be a three-way conflict between DL fetch, name fetch, and data fetch. Worse, the data fetch will be driven by a name fetch three cycles earlier in the region where playfield DMA is blocked, meaning that it'll pick up bus data from the 6502 instead.How about we disable playfield DMA in DMACTL during horizontal blank? 1 Quote Link to comment Share on other sites More sharing options...
drac030 Posted November 23, 2017 Share Posted November 23, 2017 Considering all these difficulties, "with almost no restrictions" in the topic seems to be a bit of overstatement. But the matter is interesting, any chance for a practical application (in a preview form at least) any time soon? 1 Quote Link to comment Share on other sites More sharing options...
phaeron Posted November 23, 2017 Share Posted November 23, 2017 Well... that depends on someone spending time writing and trying out test programs on the real hardware. The idea of turning off playfield DMA to suppress the conflict in HBLANK seems plausible, though I haven't checked the schematic to confirm. 1 Quote Link to comment Share on other sites More sharing options...
fox Posted November 23, 2017 Author Share Posted November 23, 2017 Considering all these difficulties, "with almost no restrictions" in the topic seems to be a bit of overstatement."Almost no restrictions" for the graphicans using it. The difficulties we discuss are for the programmer. Quote Link to comment Share on other sites More sharing options...
emkay Posted November 23, 2017 Share Posted November 23, 2017 This thread still makes no sense. Everything ANTIC does, will immediately be visible on the TV. Disabling features while ANTIC isn't doing something, also won't help "adding" features. Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted November 23, 2017 Share Posted November 23, 2017 emkay sorry but what you just said does not make sense... nothing wrong with turning off what isn't needed and only turning things on when they are needed every once in a while.... no need to light the whole house when your just reading in the den... 1 Quote Link to comment Share on other sites More sharing options...
emkay Posted November 24, 2017 Share Posted November 24, 2017 nothing wrong with turning off what isn't needed and only turning things on when they are needed every once in a while.... no need to light the whole house when your just reading in the den... But that is what ANTIC does already, without using any software. Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted November 24, 2017 Share Posted November 24, 2017 (edited) not exactly emkay, and not entirely, please allow the more positive exploration to occur. Just because things should not work based on what we think does not mean it won't work based on what we discover... let him try it all. So many things would be denied us and indeed were denied, that is until we messed with it and found it did work after all.. Edited November 24, 2017 by _The Doctor__ 1 Quote Link to comment Share on other sites More sharing options...
emkay Posted November 24, 2017 Share Posted November 24, 2017 There is so much obviously not explored on the A8. But this thread starts at approximately 40 years ago, when it was approved already that ANTIC is directly bound to the projection on the screen. Things can be adjusted line by line ... but to have a higher character density on a scanline, needs to exchange the given hardware. As soon as screen content needs to be changed, ANTIC has to read from RAM. There ARE possibilities to "shoot" registers from "outside" , but that means to have even more possibilities and leaves all CPU usage free. Quote Link to comment Share on other sites More sharing options...
Heaven/TQA Posted November 25, 2017 Share Posted November 25, 2017 Look at the VIC/VIC-2..... A lot of the possible FX are abusing or changing states in the gfx chip along the scanline. Same with the glu/Shifter of the Atari ST. Just to name some fx: - FLI - FLD - open borders on ST - sync scrolling on ST ... Just to name very few.... Have a look at codebase64 how Name features are available by abusing the hardware... I was always wondering why Atari has no holes... So Fox go on... we need more stuff like 40x40 2 Quote Link to comment Share on other sites More sharing options...
Heaven/TQA Posted November 25, 2017 Share Posted November 25, 2017 On the VIC-20 by C64 Tricks Resolution is increased... or color ram resolution enhanced to have more colorful pics etc... Quote Link to comment Share on other sites More sharing options...
Nukey Shay Posted November 25, 2017 Share Posted November 25, 2017 Too bad Atari 800 is not a Vic-20, I guess. Quote Link to comment Share on other sites More sharing options...
emkay Posted November 25, 2017 Share Posted November 25, 2017 On the VIC-20 by C64 Tricks Resolution is increased... or color ram resolution enhanced to have more colorful pics etc... So he searches the wrong chip. It would be better to search in the GTIA for a switch that allows real colors in hires, or the vertical control over the PMg . GTIA is the real weird part, looking unfinished at all, in the Atari, so there could be real unexplored stuff. Like a resolution character based switching... Every "trick" be it on the C64, VIC 20, or ST were based on fully different architectured chips. The ST with it's sheer CPU Power, the VIC by the setting for low memory... and so on. The little that is wrongly explained in the books about ANTIC doesn't really help to double the speed of a sprite based game. Quote Link to comment Share on other sites More sharing options...
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