Gameboy Development Forum

Discussion about software development for the old-school Gameboys, ranging from the "Gray brick" to Gameboy Color
(Launched in 2008)

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#1 2013-02-10 08:05:10

Drakon
New member
From: Toronto Canada
Registered: 2013-02-03
Posts: 3

Help debugging a rom

I've been messing around with the gameboy colorizer working to convert marioland into colour. I got the rom with colour and glitch free, except on real hardware it refuses to run. On the gba the rom runs in gbc mode and after the bios screen it goes white. On the sgb I get to the title screen and then it just refreshes over and over. Here's the rom:

http://www.mediafire.com/?q3438655bk680hy

What I did manage to do was I found a way to recreate what's going on in an emulator. Using the bgb emulator I click on options, exceptions, then I click on "cart troubleshooting mode". I load the rom and it gets to a couple of empty code spots which I just fill with "nop" or skip past. Once I'm past those few spots I get the same white screen as my real gba. If I go into options, system, and tell it to run as a "super gameboy" then I get the same thing happening as the real super gameboy. With the emulator in troubleshooting mode set to run as a super gameboy it gets to the title screen and gets stuck occasionally refreshing the title screen just like the real super gameboy. I could really use some help with figuring out what's causing the rom to get stuck.

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#2 2013-02-16 20:25:43

paulc
Member
Registered: 2012-10-23
Posts: 27

Re: Help debugging a rom

It seems the game has more issues than just changing the bank switching to the common/proper "ld $2000, a" (which is a common problem on the EMS carts).

In BGB, right click and select "options"->"exceptions" and select all the boxes. Any kind of error or invalid instruction will then stop the game so you can evaluate it.

If you're truly interested in colorizing a game, really the only proper way is to disassemble it, add the custom palette code, then reassemble it. I think people have done this with Pokemon. You probably don't need to disassemble the whole game. Just look for the areas that write to VRAM, usually indicated by $8000-to $97FF. If you buy a book on z80 programming you could probably complete your project in a couple months or so.

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#3 2013-02-18 09:13:23

Drakon
New member
From: Toronto Canada
Registered: 2013-02-03
Posts: 3

Re: Help debugging a rom

Thanks.  Here's the current state it's in:

http://www.mediafire.com/?199z9h288x9r4rm

I really don't get why it crashes at the end of the stage.  I got it down from 1 mbyte to 128k.  When I started this I knew nothing about asm or gb asm so I'm still trying to figure it out using the bgb debugger.

Last edited by Drakon (2013-02-18 09:14:34)

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