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Geoff Oltmans

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About Geoff Oltmans

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    Chopper Commander

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  1. Maybe depletion mode transistors?
  2. The Robotron, Dig Dug, Planet Smashers, Tower Toppler, Ballblazer, Karateka.... all of these are way too low.
  3. IIRC Digikey has some sockets for it. Nice job on your layout. I was thinking of persuing a similar card. My idea was to ditch the DRAM and use some SMT SRAM instead to make a smaller package, and to make a piggyback board to replace the internal VDP, but I like what you've done here. You'll need to write a patch to at least program the palette registers on the 9958 as by default all colors are black.
  4. A while back I was starting to do schematic capture for a Yamaha 9938/9958 upgrade board. I'd like to do one using SRAM instead of DRAM (using a CPLD to demux the DRAM addressing) to reduce part count and use more modern RAMs. I used to have a TIM board for my ADAM that I scavenged from a TI 99/4A, it worked, mostly. The first hurdle is that you must program the palette registers used by the older video modes as by default all the colors are set to black, so nothing would display. There were some other gotchas, but I like the idea of using a 9938 or 9958 on the ADAM, and I think a DIY project could be pretty inexpensive.
  5. If you wanted to do this internally, depending on what expansion cards you have you may be able to do it through one of the internal slots.
  6. Take On Me - A-Ha Money for Nothing - Dire Straights Whip It - Devo
  7. I can vouch for this... fixed me right up.
  8. Well, you mention that you're testing with the expansion boot ROM for the HD system, so you might try with that left out. I know I have had some incompatibilities with that, both on the real system and the emulator.
  9. I don't think that was it. I was vaguely remembering some details about a expansion port game that used it to support saving high scores or something, but I may be getting my consoles mixed up, or I'm just completely off base.
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