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Graphics Hardware Hacking Upgrades Hardware Build Games

TMS9918A Retro Video Chip Reimplemented In FPGA, With VGA Out 126

Posted by timothy
from the disintergrated dept.
acadiel writes "Matthew H from the AtariAge.com TI-99/4A forum has finalized a design of a TMS 9918A replacement (with VGA out) for classic computer systems such as the ColecoVision, TI-99/4A, SpectraVision, MSX1, SpectraVision 128, and Tomy Tutor Home computers. This hardware project replaces the native video controller on these classic systems and enables them to have VGA output for the first time." (It's just under $100 to order one.)
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TMS9918A Retro Video Chip Reimplemented In FPGA, With VGA Out

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  • Are you in Europe? (Score:2, Interesting)

    by tepples (727027) <tepples@gmaiBLUEl.com minus berry> on Saturday February 11, 2012 @05:56PM (#39007489) Homepage Journal

    there aren't a ton of TVs still being manufactured with VGA-in.

    Just about every LCD TV that I've seen in (U.S.) stores has a VGA input. It might be the case that you live in Europe and your local TVs include a SCART port instead. I'd bet the actual video processor in such TVs can sync to both 480i SCART and 480p-1080p VGA.

  • Re:Um.... (Score:5, Interesting)

    by tibit (1762298) on Saturday February 11, 2012 @07:05PM (#39007919)

    You're completely, absolutely, out of you mind deluded. Sorry. At work I use some test instruments, made by Tektronix and HP, where the date codes on chips are all in the 70s. They work beautifully, and I regularly "hack" on them. They are anywhere between 30 to 40 years old at this point. There's nothing fussy and temperamental about those systems, and some of them are so complex that a consumer-grade microcomputer or game console holds no candle to them. I'd say that all of the consumer systems that this chip replacement would go into are comparably simple. If you would really have a problem with them, then it's your problem, not a general one. If you want complex, take any modern PC and try replacing a BGA chip in it. I'd take a 30 year old piece of gear any day, I probably could do chip swaps in those blindfolded.

  • by Mr Z (6791) on Saturday February 11, 2012 @10:43PM (#39009003) Homepage Journal

    It's not really RGB output, but rather Y, Y - R and Y - B luma/color difference signals -- actually frightfully close to S-video. But I'm pretty sure they had an app note back in the day that showed how to sum those to get RGB almost trivially.

    The reason they went with the 9928A (and later 9128A) was to avoid the "rainbow effect" that was is prominent on the 9918A. See, the 9918A didn't flip the chroma carrier field-to-field, which leads to reinforcing chroma errors. That's also why you couldn't use the EXT VIDEO input on the 9918A to mix with arbitrary video sources (say, for a video overlay), but you could use it to daisy-chain VDPs to get more sprites and such.

  • Re:Um.... (Score:3, Interesting)

    by anubi (640541) on Saturday February 11, 2012 @11:23PM (#39009135) Journal
    Yes. I regularly "hack" my old stuff.

    Fer cryin' out loud, they even gave me schematics!

    I guess in those days they figured if you were knowledgeable enough to buy their thing, by golly you probably had the skills to fix it too.

    It was TEST equipment, meaning you were connecting it to God knows what, where only God knew what malfunctions were in it. This is a sure-fire recipe for an occasional fireworks display on the bench.

    Those were the days. I am glad I didn't miss them.

    I learned more from fixing my test equipment than I ever learned from books and exams. And I got to learn from the best... Tektronix and Hewlett-Packard.

    Like you pointed out, the BGA ( even those surface-mount IC's ) did it in for me. I could not get test prods on them, much less remove/replace them, even if I could get my hands on what soon became custom ASIC's.

    The new stuff is either factory-support or downright disposables.

    Those were the days. Thanks for another trip down memory lane.
  • Re:Um.... (Score:3, Interesting)

    by ogdenk (712300) on Sunday February 12, 2012 @12:49AM (#39009421)

    I have an Atari 400 made in 1980, an Atari 600XL made in '83 and a 130XE made in '85. Along with a desktop DEC MicroVAX of mid-80's vintage. All still work just fine with no flakiness. Clean the cartridge ports and take care of them they'll outlive you. The 8-bits may have been low cost but they were QUITE well engineered. At least the Atari machines and Commodores were great. Not sure about TI or Coleco.

    They made much higher quality caps then and used lead solder and much thicker PCB's with more copper. Later 80's 8-bits took a quality nosedive but they still weren't that bad, just had cheaper keyboards and thinner case plastics. The Amiga and ST were the major contenders by then.

    Now if you want to see shitty caps, look at late 90's, early 2000's PC motherboards. I don't know too many 600mhz-1GHz Pentium III and Athlon desktop boards still running.

    In general I find older 80's hardware much more tolerant of being repaired when necessary and with only 16 address and 8 data lines, hand soldering in modifications is relatively simple and lots of well documented hacks exist complete with code and schematics. I've added 512K, dual OS ROMs, S-Video and an IDE interface to my 600XL and it took about 45 minutes with a cheap radioshack iron and manual desoldering iron/pump. Try that on a microscopic ARM with 200 pins crammed into a BGA the size of your pinky nail attached to a 6-layer board.

  • by ogdenk (712300) on Sunday February 12, 2012 @12:54AM (#39009433)

    http://spiflash.org/block/15.html [spiflash.org]

    The VBXE video board for Atari 8-bit XL and XE machines. Will do 15khz RGB and VGA out and coexists with and extends the original video coprocessor chips (ANTIC and GTIA) providing a blitter and extending the color palette. Enhanced sprites too and more stuff. The Atari graphics chipset was much more programmable and flexible than this thing though every machine deserves to still have modern video output options. The Atari 8-bit is kinda like a baby Amiga in ways.

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