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1. NO BLATANT PIRACY. This includes reproducing homebrew less than 10 years old, with the exception of free software.
2. No advertising your reproductions, with the exception of free software.
3. Be nice. See RFC 1855 if you aren't sure what this means.



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PostPosted: Sun Dec 24, 2017 2:11 pm 
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I'm curious if anyone has had problems (or success) getting a NES-NROM-256 game running on the ReproX board. I ordered some of the boards and EPROMs from game-tech, and I've successfully created Battletoads, and Dig Dug repros. I created a NROM test board with sockets, which I used successfully for Dig Dug. I cannot, however, get a Super Mario Bros (NROM-256) repro working. I'm trying to get a SMB hack (of my own creation as a present for my daughter) working, I even tried regular, unaltered SMB (verified that CRC32 on each ROM image matches the bootgod records) and it doesn't work. It just gives me a grey or green screen. I've doubled (quadrupled, etc) the ROM images to fit the chips. I've tried both the AM27C128 and the AM27C020 chips for the CHR. I switched the mirroring. I checked the datasheet for the AM27C020, and it allows pin 1 pulled high or low. I chose high which worked for the Battletoads repro. I've polished the pins on the old EPROMs, verified the data, tried multiple different EPROMs. I'm either really unlucky, or I am missing something.


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PostPosted: Sun Dec 24, 2017 4:01 pm 
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Joined: Sun Dec 24, 2017 2:01 pm
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I did some further tests and my NROM socketed test ReproX board can run Dig Dug and Championship Lode Runner, which are both NROM-128, but can't run Super Mario Bros or Chubby Cherub, which are NROM-256. This page suggests that the mirroring is different: http://wiki.nesdev.com/w/index.php/Programming_NROM and that NROM-128 games mirror at $C000 and $8000 but generally run from $C000-$FFFF range while NROM-256 run only from $8000-$FFFF. If the PCB, as configured for NROM, only maps the PRG ROM to $C000, then only NROM-128 games would work--which is what seems to be happening. Or, possibly, one of the jumpers already handles this, and I really suck at soldering.


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