View Full Version : Dumping EPROM Protos with Willem EPROM Programmer?
01-19-2009, 07:50 PM
I just got my hands on some nes and genesis eprom prototypes and want to back them up.
I have read that this can be done with the Willem EPROM Programmer but have yet to find a guide on exactly how to do this.
Can anyone point me in the right direction?
01-19-2009, 10:06 PM
1) Remove EPROM from cartridge (desocket/desolder)
2) Insert into Willem programmer
3) Set DIPs as instructed by Willem software for indicated ROM
4) Use the read function to read the ROM into the buffer
5) Save buffer to file
NES prototypes will only use 8-bit EPROMs which are directly readable by the Willem, some Genesis may have 16-bit EPROMs which will require the 16-bit adapter. Genesis prototypes may instead use two 8-bit ROMs to form the 16-bit data bus; in that case you need to read each ROM separately then interleave the data (one byte ROM A, one byte ROM B, one byte ROM A etc...) if you don't know which ROM is high or low, you can always use a byte swap utility on the resulting file, most hex editors will have one but you're on your own to interleave the ROMs.
If a game is actually spread across multiple ROMs (only for Genesis), you'll have to figure out how the ROMs are decoded to append the dumps to each other. Most likely ROM A will be the starting address but ROM B could either be the next set of data or it could be the corresponding high/low byte of ROM A.
NES games come in two varieties: games with character (tile) data ("CHR") in ROM and CHR in RAM. If your games have "CHR-RAM" (instead of two ROM chips, there will be a ROM and a RAM), you obviously only need to dump the program ROM.
Remember that you won't be able to test your NES files until you give them an iNES header for emulators; this will vary depending on which games you're dumping, so you'll have to learn how to assemble your own header or copy the header from the retail dump of your prototype game. It will be the first 16 bytes of the ROM. From there to build your .NES file, just append the program ROM data to the header, and append the character ROM data if any to the program ROM.
01-21-2009, 03:32 AM
Thanks for the excellent info
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