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drpeter

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Everything posted by drpeter

  1. Another stunner! A question- although it seems to be for a PAL palette, the proportions of this image and many of your other recent ones seem slightly vertically flattened- see for example the very obviously elliptical moon in this one- and the proportions look more 'normal' on an NTSC display where the almost square but very slightly vertically flattened PAL pixels are instead noticeably vertically stretched. Is this because of the kit you are displaying images on? Or is it a deliberate compositional thing to vertically squeeze images into 240 vertical pixels?
  2. The way to do this is in pre-processing: produce two (or more) output.png-dst.png images with different types of (or no) dithering then combine the output.png-dst.png images into a single input image with the right kind of dithering in the places you want them and finally run Rasta with that as input and no dithering or other tweaks. I did this in my recent Stonehenge image: the sky below the clouds has knoll dithering strength 3 and the clouds and foreground low strength jarvis dithering.
  3. OK, thanks. That confirms that there are no player repositioning artifacts in that image- there are no discrepancies between output.png and the displayed xex, also Rasta Slide detects no potential player positioning artifacts. So that's a pass for @Sheddy's new Rasta version.
  4. I think this relates to use of the wide playfield setting, which Rasta doesn't currently use (it uses standard width playfield). The black quadruple-width missiles at the left and right borders of Rasta images are used currently to mask stripes created by changes to the background colour (which displays in these borders) not the 'garbage pattern' 'Virtual playfield DMA' ANTIC/GTIA glitch seen at the extreme right of wide playfields. Rasta could in theory be reprogrammed to use a wide playfield, but it would reduce the CPU cycles available for enhancing the image through register updates because of increased ANTIC 'cycle stealing' for playfield graphic DMA memory access. A wide playfield in the usual Rasta resolution would display 176 pixels (160, plus 4 extra pixels to the left and 12 extra pixels to the right) plus 2 pixels of 'garbage' at the extreme right border of the image (seen only on real hardware coupled to displays capable of fully showing these extreme widths, or on emulators programmed to display them- currently I believe only Altirra with certain display options set). It would also in theory be possible to furthermore program Rasta to use the 2 'garbage' pixels at the extreme right border of each image, using a technique similar to but slightly different from that described for the Death Of The Right Side Garbage demo- as described in detail here- but this would eat up further CPU cycles, so again the result would be a marginally wider image (178 pixels vs 176 pixels) but at the cost of some degradation of the quality of the rest of the image. So, yes, these things are possible but I doubt anyone is going to implement them as options to Rasta any time soon, as unfortunately those with the requisite skills have repeatedly said they don't have sufficient time or interest to invest in making further improvements to the app.
  5. Could you post a zip file of the Generator folder, perhaps? Shouldn't be ANY artifactual stripes, so would be good if we could look at the code for the screen kernel as well as the output.png rendition... (Stripes present in output.png as well as the xex rendition are due to limitations of the Atari hardware/rasta process, not bugs, and so are not artifacts in quite the same sense)
  6. I think Atari made a fundamental business model error right at the launch of the A8 line, which was to continue the strategy they had established with the 2600 of guarding the advanced hardware specs as closely as possible in order to keep development of high-quality commercial software that could be sold at a premium in-house. The emphasis should rather have been on growing the ecosystem as quickly as possible in order to achieve a dominant market position by transparently showcasing the years-ahead-of the competition hardware capabilities while assisting 3rd-party software development as much as possible.
  7. RF input to 'modern' LCD TVs from all Atari 8 bits often looks rubbish like this. I'm not sure if it's to do with signal strength, signal processing or what. The vertical bands down the left side of the screen are probably due to a poorly-designed RAM expansion board interacting with ANTIC DRAM refresh memory accesses. I had a 32K RAM expansion board in a 400 back in the day with this exact problem.
  8. Hercules Workshop website, Twitter and eBay shop all still seem to be down. Anyone by any chance got a spare 5-pin DIN to S-video, composite video and audio cable they no longer need & willing to sell? Alternatively, anyone know of an alternative source for double-shielded AV cables like this? I am located in the UK.
  9. Can second this- just spent 2hrs googling and searching before reading this post, and this was the one I landed upon. 3000mA AC/AC supplies are not easy to come by, especially at a reasonable price, and 2000mA should be fine for both computer and peripherals- the 1050/810 disk drives might draw very transient higher loads during start-up but that won't cause a problem, both in theory and in practice in long-term use, as reported on this forum. www.poweradaptorsuk.co.uk do actually advertise a 3000mA adaptor that is similarly priced and doesn't need an adaptor, but it's currently out of stock (don't know when or if it might reappear)
  10. Hi, could you possibly post the full instructions or link for this mod? best wishes, Peter
  11. Urban Fox 31 colours. drpeter_Urban_Fox.xex
  12. Yeah, that's a Type 4. Not all of them have rough keycaps.
  13. Great image. The chessboard dithering you are putting on some of these conversions is very effective. That's definitely not a sperm whale or a blue whale though! I think it's a humpback whale.
  14. Stonehenge 22 colours drpeter_Stonehenge_Sunrise.xex
  15. On a real Atari, this is true- the details of why are described in the Altirra Hardware Reference manual. Wide/extended height playfields were never part of Atari's marketing, I don't think.
  16. The Atari has modes which increase or decrease the standard horizontal resolution by 20% (by increasing or decreasing the horizontal width of the field in which graphics are displayed, not by narrowing or widening the pixels) which would for example give modes of 192 or 128 pixels wide rather than the standard 160 pixel mode, or 48 or 32 characters wide rather than the standard 40 characters. See the Altirra Hardware Manual or De Re Atari for details.
  17. Another to add to the collection of superb Rasta conversions of Tutankhamun on here!
  18. We already had a 16K 400 and 410 recorder on order courtesy of my parents, but stock wasn't yet available. The 400 arrived in Spring 1981, several months ahead of the 410, and during that time we had no means of saving the programs we typed in!
  19. Back in late 1980 the A8 line was yet to hit the shores of the UK, but in the run-up to Christmas Maplin- roughly the UK equivalent of Radio Shack- brought some pre-launch demo systems on tour, and my brother & I were taken by my indulgent parents to a hotel in central Manchester to take a look. And that's when I first saw, and briefly got my hands on, Star Raiders. There was nothing like it, even in the arcades, and even just piloting through the 3D starfield, dodging asteroids, felt astonishing. The dogfights were immersive, the ever-present threat of sudden death (even with shields on) gripping, the numerous skills and multiple systems to master (including learning to deal with damaged systems), the blend of shooter & strategy, it was so ahead of its time- and crammed into 8K of ROM and with little more than 3K of RAM to work with on an 8K system after graphics RAM usage etc. Star Raiders is essentially a 3D real-time graphic version of the old mainframe terminal game Star Trek, and its influence can in turn clearly be seen in the later smash hit for the BBC Micro (and later other platforms) Elite, which embraced the concept and ran with it. After that trip to Manchester, my brother and I scraped together the at-the-time astronomic £30 to buy it. Astronomic, but nevertheless turned out to be one of the best-value purchases of my life. One of my go-tos even now- still 43 years later using that original 1980 cartridge.
  20. The (non-default) settings I used were: palette=altirra dither=jarvis dither strength=0.5 contrast=30 number of solutions=10000 You might want to try running your edited source image again, with those settings?
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