Patching Game Genie into ROM

[evildragon]

I can't seem to get this to work.. I want to patch some game genie codes into ROM, so when I put a game onto a flash cart, the game is already patched..

But everytime I edit the ROM, the emulator or console just boot to a black screen..

I'm lost here..

[Jorge Nuno]

Maybe you need the fix the checksum or hack the checker routine. Just find the "Autofix checksum" in the emu and see if it works.

[Tony H]

Yes, you're getting the black screen because you've changed the checksum. A few ways to fix that. Like Jorge mentioned, see if your emu has a checksum fixer. If it doesn't, look on the internet to see if the game you're having problems with has a "Master Code" type Game Genie code. Master codes either make the game skip the checksum process, or make it so that it ignores the fact that the checksum check has failed. Hack the master code into the ROM and you're all set.

If you can't find a Game Genie type "Master Code" for a particular game, let me know and I'll make one for you.

EDIT: If you're the Do-It-Yourself type, I wrote a guide on making master codes:

http://codehut.gshi.org/ImprovedMasterCodes.txt

[evildragon]

I actually tried a program I found that fixes MD/Gen checksums, and it worked, the game now loads, even on real hardware..

[David J.]

Hey, I tried the Game GEnie Code converter and I noticed a few quirks:

When I copy and paste a code or input one in the Code Input, it is in a diff order in the patch select, but if I swap it and hard patch my game, it is fine... why does it swap? Also, I tried this code for Ichidant-R to change the region:

AADA-AA8N
REDT-A60C
REDT-A60E
REDT-A60L
REDT-A60N

But any code that is more than four lines long will not show up in the program, and even if I input a code that is four lines long it will appear out of order when I see it in patch select so I have to mess around. I have six more games I want to patch but ugh this program is kinda bunk. I want to hard patch the games but these last six are a pain in the butt

[goldenband]

Hey, I tried the Game GEnie Code converter and I noticed a few quirks
I just use this Java applet:

http://games.technoplaza.net/ggencoder/java/applet/

It's a little quirky too, and you have to enter the codes one at a time, but it's always worked for me.

[Tony H]

Also, I tried this code for Ichidant-R to change the region:

AADA-AA8N
REDT-A60C
REDT-A60E
REDT-A60L
REDT-A60N



Here's a much shorter version of the Ichidant R (J) regional bypass Game Genie codes...

AJCA-AA46
Lets you play the Japanese cartridge on a US Genesis or PAL/European Mega Drive.

AADA-AA8N
Master Code (use this code if you get a message that says "Check Sum Error").

Let me know if they work for you.

[David J.]

It worked. Last two games are Contra and Alien Solider but I'll try the site above.

THANKS!

Last game is Alien Solider (J) but I found a post on how to adjust the music for the PAL version. Cool stuff.