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Genesis repro with 40 pin eproms
http://forums.nesdev.com/viewtopic.php?f=23&t=14996
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Author:  lemonpotato [ Fri Oct 28, 2016 3:53 pm ]
Post subject:  Genesis repro with 40 pin eproms

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?

Author:  tepples [ Fri Oct 28, 2016 4:13 pm ]
Post subject:  Re: Genesis repro with 40 pin eproms

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])

Author:  tokumaru [ Sat Oct 29, 2016 6:28 am ]
Post subject:  Re: Genesis repro with 40 pin eproms

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.

Author:  e-neon [ Mon Oct 31, 2016 10:18 am ]
Post subject:  Re: Genesis repro with 40 pin eproms

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.

Author:  lemonpotato [ Thu Nov 03, 2016 7:43 am ]
Post subject:  Re: Genesis repro with 40 pin eproms

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 .. :)

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