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About dmlloyd

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    Chopper Commander

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  1. The diagram I am working off of (Julie Solomon, 9/19/1983) shows 176 color cycles / 88 machine cycles displayed for wide. I haven't tested it first hand though; I just assumed that the diagram was accurate. Ah that one is definitely a mistake on my part. Hmm again the diagram I have shows four gaps between the last LMS fetch and the first character fetch. Fixed that one in rev 2, I don't know why I did it that way. Hmmm. No hint of that in my original here. I'll look into this. Good to know... again, this original diagram... Ah I must have counted wrong, will fix that one. Interesting! Nice, that's much better than mine. I guess I will continue to fix this one up though, because, well, I've gone this far... It's interesting that this original diagram is so inaccurate (my mistakes aside). I wonder if any games/programs were designed with this inaccurate information, and then exhibited inexplicable bugs as a result. I never was able to figure out who Julie Solomon was, or where she worked. Thanks for the great feedback.
  2. Cool, I didn't think of adding HSCROL offsets on there. Maybe I'll see how hard that is to do. Next rev I'll export SVG and put it in a zip, thanks for the idea.
  3. Here is version 2 with some fixes.
  4. Not dumb questions at all. Unfortunately the tool I used doesn't have a "legend" function (AFAIK anyway). So here's the translation: The orange "R" boxes are memory refresh cycles; CPU is halted but it's a refresh address on the bus, not a graphical data address. The yellow "M" and "P0".."P3" boxes represent memory fetch for player-missle graphics, if enabled. Boxes labelled "C#" are memory fetches for characters. Boxes labelled "D#" are memory fetches for graphic or character set data. The top/bottom numbers are the horizontal cycle count. The transition on the WSYNC line represents when ANTIC "releases" the CPU after it writes to the WSYNC register. The HSYNC/HBLANK lines correspond to the display signals of the same name. The "memory fetch" lines represent which cycles correspond to which playfield widths. As an aside, I did notice that the refresh cycles on the first couple rows are wrong, and there's a spacing problem, so I will fix that for rev 2.
  5. After a frustrating day at work, I took some time to do something I've had on my list for a long time: I made a new version of an ANTIC horizontal line timing chart that I believe was posted here many years ago. The original chart was very complete but also unfortunately rendered at quite a low resolution, making it very difficult to read. I augmented the chart with a couple bits of data from the ANTIC data sheet, and, well, here it is. I have an SVG version of it too, but AA won't let me upload it. The drawing was made with the WaveDrom editor. Anyway, I would appreciate it if any experts might check it over for errors.
  6. I'd like to just point out that for less than $20, you could have a much simpler programming model (and simpler logic too): http://www.digikey.com/product-detail/en/CY7C006A-20AXCT/CY7C006A-20AXCT-ND/1205394 EDIT: That's high-quantity pricing, but this kind of part is not that much more in single units...
  7. That way you can violate two copyrights at once
  8. FujiSkunk, you can change the color qualities of artifacting by choosing a different color value for the background, which will effectively mix the effect of luma artifacting with the normal color output of the GTIA. For my test I chose black and white to provide the sharpest contrast possible, which will allow a better identification of the relative phase shift of the luma output.
  9. Okay here's another version which displays color bars for comparison. artif.xex
  10. Wow, that's a greater variation than I was expecting. I think I have an idea for improving the test...
  11. In addition to being actually runnable from DOS, this one is modified to be able to run in 16K. artif.xex
  12. Whoops! I just tested that it would run in emulator, totally forgot to give it a RUN address. Will fix.
  13. Yes, I did explain in my original post that the artifacting color is caused by the delta between the color signal and the luma signal. What I'd like to gather data on though, is what actual hardware outputs what artifact colors. An emulator will of course display any color you tell it to.
  14. This gives the opportunity for an interesting experiment though. Anyone who is willing and able, run the attached XEX and post a screengrab of the output along with your machine type and CTIA/GTIA information if possible (including the part number + -suffix, mfr location, and date code if possible). This XEX should work on any atari with at least 32K of RAM (it loads at $2000 and uses $4000 for graphics). artif.xex
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