Hi all! I recently discovered a cool visual patch for the Super Game Boy 2 (https://www.romhacking.net/hacks/6449/) that according to the documentation, MIGHT work on actual hardware via an EEPROM. I'm itching to try. I've looked at the PCB compared it to the schematics for the original SGB (found on gbdev wiki); I've read all I could find on teardowns of the SGB2, but I'm still unsure about which chip has the rom for the software that I want to replace and which one has the smaller bootrom that checks the Nintendo logo on startup. Does anyone have any guidance?
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Sweeeeeeden
The chip you're looking for is the one marked SYS-SGB on the chip. The smaller boot ROM is situated inside the CPU chip and can't be replaced. It should be as simple as looking at the schematic on the GB Dev wiki (run by me btw!) and...
- Follow all the "SA" signals to the corresponding "A" signal on the EEPROM.
- Follow all "SD" signals to the corresponding "D" signals on the EEPROM.
- Connect "/RCS" to "/CE" or "/CS" on the EEPROM.
- Connect "/ROE" to "/OE" or "/RD" on the EEPROM.
- Connect any "/WR" pin on the EEPROM to +5V.
- Connect gnd/power.
- Connect any unused address pins to ground.
I say simple, but this would be very tedious work, especially if it's the first time you're doing something like it. Here's a potentially better idea. Use PinoBatch's Border Crossing to set the border/palette and do a cartridge swap. You'd need to add the graphics in question to the Border Crossing ROM somehow, but might still be easier than swapping the ROM, and maybe more importantly, doesn't have the risk of destroying a perfectly good Super Gameboy.
I made a ROM for making EZ Flash Jr work on SGB. (Hey, second self name drop in this post.) It wouldn't be too much of a stretch to add support for setting the SGB border/palette from that if anyone is interested.
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Puerto Rico
Yeah! I got border crossing working on SG2 with a usb EMS cart, now I just have to make my own version of the rom with the borders flamepanther made and use a tool like this:
https://slashinfty.github.io/sgb-colors/
I have an ezflash jr on it's way to me, so adding that functionality to your enabler rom would really be appreciated over here.
Offline
Puerto Rico
SGB palette codes for the vaporwave edition palettes:
1a 0691-3219-5267
1b 7316-5716-2342
1c 0126-5466-9724
1d 6412-1206-5267
1e 0692-0907-5278
1f 0205-2666-2664
1g 2081-3212-8194
1h 6672-0719-5290
2a 0807-1422-1330
2b 0697-2073-2385
2c 6421-3165-0321
2d 6411-4706-4916
2e 7272-0071-4714
2f 0830-6766-4203
2g 0190-0919-5724
2h 0371-3115-7912
3a 6410-6572-2201
3b 7150-8316-0713
3c 6416-0015-9338
3d 0196-0464-6267
3e 1336-5766-2321
3f 0826-4713-1287
3g 1486-6421-4278
3h 6670-0013-0706
4a 1437-1071-4267
4b 7175-8207-3278
4c 0500-6716-0267
4d 7312-1227-6330
4e 0841-4619-3194
4f 3291-9373-3203
4g 6561-9526-6331
4h 2002-6477-4331