Diablo [Gameboy] [Unreleased - Tech Demo]

Still trying to decide if Ill hold onto this and do a community dump, or just sell it to someone who wants to hah.

 

I'm curious to see what lies beneath the surface. Wonder if this could be turned into a working game by the right guy.

 

Parallel cable on the way to have it dumped Pass that, I still dont know what Im doing with the game, as there is another interest Id like to persue hah.

 

Great You can mention on your website that you're looking to sell it, and if you get no buyers, you can donate it to a museum

 

Well that all depends on if I can get cash another way or not hah

 

For sale thread up, like I say, it depends on if I can sell a few other bits and pieces.

 

hmm an empty chest.

Does that mean you are out of cash?

 

Well Im always out of cash. But the games dumped now

 

Ahh....so what did you find?

 

Havent really looked yet, just glad to have it dumped

 

cool

 

Disassembly is indeed the meat of figuring out a game, but hex editors are more useful than you might think. When I have a game that I want to hack, I have my own methods. The absolute first step is to make a text file with headers for all the banks... GBC games consist of banks of 4000h bytes.

I generally start by finding the text. One way is, if there's any sort of text input or name selection screen, to input a name and then compare a RAM dump via a hex editor. If there isn't anything like that, relative searches (a function available in most hex editors) work quite well unless the font is hugely out of order. Through a bit of experimentation either of those methods can make a complete list of what byte value corresponds to each letter or control code, and thus a table file can be created. Using a hex editor I open the table file and look for text, noting it in my list of ROM offsets and information.

At this point I generally use a program such as Tile Layer Pro to view tiledata. Offsets are found by modifying the first tile of a bunch of tiledata, and using Windhex's compare function with a clean dump. Again, I list the offsets in a text file.

Next I start working with RAM addresses, using VBA's memory viewer to find bytes that change based on various conditions. This is best used for on-screen coordinates, health values, money values, and the player's name (as well as enemies onscreen). Occasionally I stumble across good finds, such as what byte determines the music or, better yet, warps.

Now it's basically an open field. Generally searching in a hex editor for pointers/RAM addresses is good for finding ASM code, and I like to disassemble by hand. This takes longer than using an actual disassembler, but has the advantage that I usually know what's going on at this point and thus can comment the code very easily. no$gmb works great for debugging as well. (On a side note, it doesn't take much effort to memorize several of the opcodes for a particular system. E.g., CDh is "call YYXX," C9 is "ret," and "x1" is "ld rp,$YYXX".)

So yes, disassemblers are somewhat useful, but they can't be used to collect pure data such as text. That's why you should use multiple tools.