Genesis repro with 40 pin eproms

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Genesis repro with 40 pin eproms
by lemonpotato on 2016-10-28 (#181467)
Hey there,
I want to make a Genesis repro of Contra Hard Corps, but I only have a MiniPro EPROM programmer at hand, which means I can only program 40pin EPROMs and not 42 pin EPROMs.
Is there any way to create repro of a 16Mbit Genesis game by connecting two 8Mbit EPROMs with each other, similar to the SNES?
I already read about lower bytes and higher bytes that would need to go on each EPROM separately, but I haven't been able to find any tool that handles that or any tutorial that shows how to do it. (wiring, pins etc.)
Does anyone know more about it?
Re: Genesis repro with 40 pin eproms
by tepples on 2016-10-28 (#181468)
To use 8-bit EPROMs, you'll need to deinterleave the ROM. Here's a deinterleaver in Python:
Code:
#!/usr/bin/env python3
import sys

infilename = "Sonichu the Electric Hedgehog.gen"
evenfilename = "Sonichu-hi.bin"
oddfilename = "Sonichu-lo.bin"

with open(infilename, "rb") as infp:
    data = infp.read()
with open(hifilename, "wb") as outfp:
    outfp.write(data[0::2])
with open(lofilename, "wb") as outfp:
    outfp.write(data[1::2])
Re: Genesis repro with 40 pin eproms
by tokumaru on 2016-10-29 (#181486)
I guess you basically put the low bytes in one chip, the high bytes in another chip, then connect all inputs to both and form the 16-bit output from the 2 8-bit outputs.
Re: Genesis repro with 40 pin eproms
by e-neon on 2016-10-31 (#181694)
I bought one of these adapters for my minipro and it works great! The design is open source so you can even have them manufactured yourself if you'd like.
Re: Genesis repro with 40 pin eproms
by lemonpotato on 2016-11-03 (#182277)
e-neon wrote:
I bought one of these adapters for my minipro and it works great! The design is open source so you can even have them manufactured yourself if you'd like.

Thanks for the tip! Unfortunately it's not sold any longer and I haven't found any other stuff on eBay.. I don't know if I'm actually capable to assemble it myself .. :)