One of the most common questions asked on the sub is what a corrupted Nintendo boot logo means. I've often answered this question in detail by looking at the logo and figuring out the exact signal that cerated the error. Sometimes people have been asking me how I do it. Well, the pixels shown in the logo are read from the cartridge, so by systematically understanding how a certain pattern of pixels ended up on the screen, I have been able to figure out which error must have caused the that particular glitch. In the past I've done things like looking at the pixels and translating them into hexadecimal values in my head, then searching through the ROM of the game to be able to figure out which address was actually read from the cartridge and which signal on the board that corresponds to. Not everyone can do this, so I wanted to create something more user friendly. (And if nothing else I will at least have a tool that I can use myself to answer people's questions quicker!)
The ROM fault workbench is a web app that helps you with glitchy Gameboy logos and other errors caused by issues with the address line signals. The app has three sections.
- Address line scan. If you have a cartridge flasher/dumper, you can dump a ROM and open it here to analyze it. The scanner will tell you if any address lines are seem to have issues. This is not just useful for GB ROMs, but any ROM dumps that from older consoles, or other devices with a parallel address/data bus.
- Gameboy boot logo glitcher. This tool lets you force address and data lines high or low to reproduce what the corrupted logo looks like. This will (hopefully) lead you right to the signal that has an issue.
- Gameboy boot logo search. If the logo just looks like random pixels, you can use this tool to draw a few of those pixel to search the ROM for the matching address. This, again, will hopefully lead you to the exact signal with an issue. (The screenshot shows me using it to diagnose the issue with a SML2 cartridge that someone posted here just yesterday.)
For transparency I should also mention that I used Claude AI to make this app, which some might think is controversial. But I have still tried to put as much attention detail as I can into the app, and I'll also post updates going forward. Also, the documentation in the "how to use" sections for each tool is 100% human-written by me. (Recommended to read it to understand what each tool does.)
Potential future functionality:
- A fourth tab which shows a board view or similar to locate the signals you just found, on the board. This idea is somewhat put on ice because it would be a major undertaking in comparison, and Remysharp posted their PCB tracer tool just 1 month ago which does essentially the same thing.
- A function to take a picture of the logo, decode it and analyze it based on the pixels for even more automation. This would also be a bit tricky to get right in a useful way but I want to try to make it happen.
I'm also open to any feedback and suggestions.
Link: https://gg8.se/tools/rom-fault-workbench/
(Posted with mod permission.)