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  • Joined: 28 Sep 1999
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ROM Pinout
Post Posted: Tue Oct 16, 2001 5:00 pm
I'd like to modify my Phantasy Star cartridge to work with a 512K flash memory chip I've got. (the Am29F040B, which has a very similar layout to a regular 27C040 EPROM)

Trouble is, I don't know what the pinout for the 512K ROM used in the Phantasy Star cartridge is. (Mine says 'MPR-11711' on it) Does anyone know?

Not that I need test programs as large as 512K, but I want to be able to play with the backup memory and paging registers. :)

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  • Joined: 21 Apr 2000
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  • Location: Newcastle upon Tyne, England
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Post Posted: Tue Oct 16, 2001 5:20 pm
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> I'd like to modify my Phantasy Star cartridge to work with a 512K flash memory chip I've got. (the Am29F040B, which has a very similar layout to a regular 27C040 EPROM)

> Trouble is, I don't know what the pinout for the 512K ROM used in the Phantasy Star cartridge is. (Mine says 'MPR-11711' on it) Does anyone know?

> Not that I need test programs as large as 512K, but I want to be able to play with the backup memory and paging registers. :)


Hi Charles,

The ROM pinout is <a href="http://www.mikeg2.freeserve.co.uk/masterful/rompin.txt">here</a>. It's much the same as the 27c040 EPROM.

Mike
rompin.txt (614 B)
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Post Posted: Tue Oct 16, 2001 9:59 pm

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> The ROM pinout is here. It's much the same as the 27c040 EPROM.

Thanks for the info, I finished the cartridge and it works - sort of.

32K games run fine on my Genesis w/ PBC and SMS 2, but anything larger (I tried a 128K and 256K game) give a 'software error' on the SMS and don't run at all on the Genesis. (I get a solid white screen)

The only thing I did a little differently was leave the NC and A18 pins unconnected, since these were the #WE and A18 pins on the flash RAM chip. (but reversed, so I'd have to add two wires to swap them around)
I figured this would limit me to 256K, but I'm wondering if that has something to do with the problems I've been having.


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Fixed
Post Posted: Wed Oct 17, 2001 7:40 am

I hooked up A18 and that solved all the weird problems - tried 15 or so games and they all worked fine.
The software error was a BIOS issue, (forgot about that completely) nothing a hex editor can't fix. :)

The neat thing is the mapper chip used in Phantasy Star seems to support paging for all three banks, so even games like Space Gun and Rastan work, which use pages 1 or 2, instead of just 3.


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