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kyuusaku · Joined: 26 Jul 2003 Posts: 941 Location: .ma.us

Going by pictures would be really hard to get right. You should definitely stick with the diagrams and only proceed when you're confident in being able to identify signals (by tracing them from the cartridge pins) and willing to cut the traces.

Using a 27C040 is very similar to the 27C801 (27C080) but it's half the size. If you don't want to put a 4M (512 kilobyte) game on your cart, you'll need a circuit to select one of multiple ROMs (which will let you play games greater than 4M) This can be achieved with a 74XX138 or 74XX139. You would connect the address lines A19 and A20 to A0 and A1 respectively on the '138 or '139, and then connect the first ROM (containing the first 4M) to Y0, connect the second ROM to Y1 etc. Using a '138 will let you use eight 27C040 to achieve 32M (4 megabytes). Using a '139 would let you use four (or more in a more complicated way) ROMs to get 16M. Most games translated I would assume to be at least 16M. I think you'll definitely have troubles using 4M ROMs since getting all those inside the cartridge will be difficult and it will be hard to wire.

If your console is NTSC, and the game you sacrifice for the translation is also NTSC, you don't need to do anything with your lockout chip. If you want to play PAL games (with a PAL lockout chip) on your NTSC console you do. If you put a PAL game into your NTSC sacrificed cart, you don't need to disable the lockout chip because you're using a NTSC one but you would probably need to put a 50/60Hz switch on the console too since many games have protection against being run in the wrong region.

xxkirbyy · Joined: 11 Jul 2007 Posts: 3

xxkirbyy · Joined: 11 Jul 2007 Posts: 3

blackrabite · Joined: 01 Dec 2007 Posts: 2

Hey there! I was just curious if you could tell us how the cart-building went. Hopefully, all went well. Now for my own questions:

My best friend and I also are very interested in modifying a cart. Let's take, for example, Seiken Densetsu 3, since that is what snesdev wrote on.

First of all, I know I need 4 pieces of 27c801 8 megabit eprom. Could somebody kindly evaluate this eprom and let me know if it would work?

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=230179962858&ssPageName=STRK:MEWA:IT&ih=013

Thanks for anybody who can help me out. I know I'll have some more questions after this one, but I'm very interested in learning how to do this!

Sincerely,
Ben