SoundGammon Posted August 18, 2020 Share Posted August 18, 2020 I just broke open a Parker Brothers Popeye that I plan to put a hack of it into and I see it uses 2 2764 eproms with NO select chip, 7404. How is it that it doesn't need one but Atari cartridge eprom games do? Quote Link to comment Share on other sites More sharing options...
ClausB Posted August 20, 2020 Share Posted August 20, 2020 Depends on how they map the game code. The cart slot has two 16K chip selects. If they map each 8K EPROM to a separate select line then they don't need an inverter chip. Quote Link to comment Share on other sites More sharing options...
ClausB Posted September 3, 2020 Share Posted September 3, 2020 I disassembled Popeye and found the code is located in the $6000-$9FFF range. The 2 cart slot chip select lines map to $8000-$BFFF and $4000-$7FFF, so Popeye does cross the boundary and make use of both select lines. Some (most?) 16K games map to $8000-$BFFF, using only one select line, so they need an inverter chip when burned into 2764 EPROMs. Quote Link to comment Share on other sites More sharing options...
SoundGammon Posted September 3, 2020 Author Share Posted September 3, 2020 Is there a diagram has to how to wire in the inverter chip? Quote Link to comment Share on other sites More sharing options...
ClausB Posted September 4, 2020 Share Posted September 4, 2020 We both noted that Popeye doesn't need the chip. Are you asking about another game? Quote Link to comment Share on other sites More sharing options...
ClausB Posted September 13, 2020 Share Posted September 13, 2020 You're welcome. 1 Quote Link to comment Share on other sites More sharing options...
SoundGammon Posted September 13, 2020 Author Share Posted September 13, 2020 What I want to do is put hacks into extra carts, like these extra Pac-Mans I have. Also, I want to do Realsports Football and change the names of "HOME" & "VISITOR" to actual team names! Quote Link to comment Share on other sites More sharing options...
ClausB Posted September 14, 2020 Share Posted September 14, 2020 I disassembled Pac-Man and Football and found they are both located between $6000 and $9FFF just like Popeye. So your hack won't need any inverter chip. Quote Link to comment Share on other sites More sharing options...
ClausB Posted September 15, 2020 Share Posted September 15, 2020 I should clarify: if you intend to put two 2764 EPROMs into the Pac-Man cart then you don't need another chip. You do need to rewire a few signals though. If you want to put in a single 27128, then you will need another chip for the select logic. Quote Link to comment Share on other sites More sharing options...
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