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The game's coding doesn't care what the padding is. Mirroring the ROM rather than padding simply ensures that the ROM operates properly if the upper address lines are left floating. However, for a 24 Mbit ROM on a 32Mbit chip, this won't be an issue. In that case, you don't even have to pad the ROM ...

Caveat: I have never made a SNES repro. My understanding is that odd-sized SNES games need to be padded as follows: * take the first 2ⁿ bytes, where n is as large as possible (in this case, 2ⁿ=2MiB) * take the remainder (which AFAIK is always 2ⁱ, i<n), repeat that part 2⁽ⁿ¯ⁱ⁾ times * result is an i...

The Mask ROM is always the same. Take a look at that diagram and you'll see that even between the 32 and 36 pin versions, all of the pins are the same except the extra 4 on the one end (you can even see it marked on 36-pin boards where you could put a 32-pin one in instead if you didn't need a large...

Yes, the wiring is different depending on the chip used. A lot of the chips use standard pinouts, but even then, the "standard" pinout can be different depending on the capacity of the chip (in the case where you have 2 different capacities with the same pin count). Check the datasheets an...

EEPROMs were around before Flash technology, so Flash ROMs are usually considered a separate technology. EEPROMs run on 5v, where most Flash ROMs run on 3.3v. Converting a 3.3v ROM to work with the SNES (which expects 5v logic) is a real pain. However, there are a few 5v Flash ROMs (the AM29F032 bei...

Is THIS the chip you're talking about? I notice it's an eeprom, while the 8 megabit chip I was looking to use is an eprom, it's safe to mix eeproms and eproms right? The SST39SF040 isn't an EEPROM, it's a Flash ROM (which, I suppose is technically an EEPROM, but you don't typically call Flash ROMs ...

As far as doubling up the file to fill the ROM, maybe I can help explain that. Think of the address lines as though they were switches. Take the highest address line and if you turn it on, you are pointing at the "top" half of the ROM and if it's off, you're pointing to the "bottom&qu...

It works out to be about $6 for both chips, vs $12 for the 29F032 and TSOP adaptor :D With regards to brands, obviously AMD is a good choice for the 27C040. For the 27C801, I've got a choice between ST, ATMEL, MXIC and NEC. NEC is the only brand I recognise there, so them maybe? They're all DIP32 w...

Here's the best free, lightweight hex editor I've found: http://mh-nexus.de/en/hxd/ Play around with it, just keep a backup of the original file and you should be fine. It's fairly trivial to copy/paste.

As far as putting a small game on a large ROM, it doesn't hurt to mirror the ROM file to fill the chip. If it's a power of two in size (1, 2, 4, 8, 16Mbit) just copy the entirety of it using a hex editor in order to make it 32Mbit. If it's not a power of two (12, 24, 28Mbit, etc), you first copy the...

More than likely, for anything above 4-8Mbit, you'll need multiple (E)EPROM's with a decoder to select between them. If you only need two, try stacking them one on top of the board, one on bottom, then clip the legs short on the bottom one.

Pin 3 is G F E' D' C B A + G' F' E D C' B' A Are you sure on this? caitsith's documentation has pin 3 NC. http://www.caitsith2.net/snes/flashcart/cart-chip-pinouts.html#mad Well... I suppose that just because the pin isn't connected has no bearing on the logic for the pin, I just want to confirm th...

No, N64 carts won't help. They use a much more interesting method of multiplexing the address and data lines which is entirely unlike the SNES. And yes, the 29F032's are obsolete as well, I was saying that if I were to use obsolete parts, that'd be my first choice. As it is, the Micron parts I'm loo...

fireaza wrote:My understanding is patched ROMS will ALWAYS give a bad checksum since you've altered the ROM

The patch can include a new checksum value. Just a lot of times ROM hackers don't bother.

I just checked my SD3 ROM, and it seems that the patch doesn't fix the checksum, so you should get a bad checksum on the patched ROM. In case you want to compare, the CRC32 on my patched, unheadered ROM is 7DBDE871 (CRC32 != internal checksum). After manually fixing the internal checksum, I get a CR...