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04-27-24 12:12 AM |
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| Main - ROM Hacking - Chalvo 55 | New thread | New reply |
| Naulahauta |
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 Red Paragoomba Level: 19 Posts: 8/56 EXP: 30495 Next: 5282 Since: 10-27-09 Last post: 3705 days Last view: 486 days |
READ LAST POST, IT'S FAR BELOW
Chalvo 55 is a fun Game Boy game released only in Japan. I've gathered some notes from it as an effort to spark motivation for a possible editor. Let's begin! When we jump to 0x18000, we see the bytes of the very first room of the game. Observe:
The bytes correspond to the tiles. Even the sprites (the blocks and the enemy) are defined in the byte array! You can edit these bytes how you wish and the changes will take place. The physical maps are also pre-defined, so blocks will always be blocks and diamonds will always be diamonds. But how do we know what blocks do the bytes represent? Let's head over to 0x18C00. I won't paste all of the definitions, but just a few to give you an idea what I mean: 02 02 FF FF FF FF 02 02 66 67 86 87 02 02 A6 A7 C6 C7 02 02 A8 A9 C8 C9 02 02 B0 B1 D0 D1 FF FF A8 A9 96 97 FF FF 70 71 98 99 FF FF A8 A9 96 97 02 02 70 71 90 91 02 02 FF FF FF FF 02 02 7E 7F 9E 9F 02 02 C0 C1 C8 C9 02 02 7C 7D 9C 9D 02 02 0D 0E CE CF FF FF 1B 1C 3B 3C FF FF 40 41 60 61 FF FF 80 81 A0 A1 02 02 AA AB CA CB Compare it to the graphics page found in 0x48000. You can view it in Tile Molester or whatever you like. 
So let's take the first 6-byte combo, 02 02 FF FF FF FF. The first two bytes, '02 02' mean "this is a tile, not a sprite". The four bytes after that define the 8x8 tiles used to build the block. This block is constructed from FF, FF, FF and FF. It is the single 'air' block. And since this was the first defined block, it is '00' on the level block data array. Check back on the map on the beginning of the post; where there's air, there's 00s. The next one, 02 02 66 67 86 87, is a crumbled block. If you look at the tilemap and take tile 66, 67, 86 and 87, you will make that very block. This is 01. Once again, if you look at the data array up there, there are 01s here and there, and each is a crumble block. But now, let's jump to the ones that begin with FF FF. That means "This is a sprite". The first FF FF-prefixed combo is FF FF A8 A9 96 97. Take tiles A8, A9, 96 and 97, and what do you know, you build a pink block similar to the one seen in the left and right edges of the first room. The behavior is defined elsewhere. And this is block number 05, so using 05 anywhere in your level will bring that pink block sprite right there. Simple as that! Another fun thing is that if you change that FF FF prefix to 02 02, the enemies turn into stone: 
Right now I've gotta flee but I'll be back later today with more data. Stay tuned! ____________________ oh |
| blackhole89 |
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 The Guardian Moloch whose eyes are a thousand blind windows! Level: 124 Posts: 3118/4196 EXP: 21533893 Next: 302708 Since: 02-19-07 From: Ithaca, NY, US Last post: 472 days Last view: 84 days |
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| Kawa |
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 CHIKKN NI A BAAZZKIT!!! 80's Cheerilee is best pony Level: 138 Posts: 3678/5344 EXP: 30946235 Next: 716746 Since: 02-20-07 From: The Netherlands Last post: 4498 days Last view: 2634 days |
That's one easy-ass format as far as it's described here. If I had a library for Gameboy graphics, I'd make that editor in no time! ____________________ Wife make lunch - Shampoo Opera - give it a spin Spare some of your free time? <GreyMaria> I walked around the Lake so many goddamn times that my sex drive was brutally murdered Kawa rocks  — byuu |
| Naulahauta |
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Red Paragoomba Level: 19 Posts: 9/56 EXP: 30495 Next: 5282 Since: 10-27-09 Last post: 3705 days Last view: 486 days |
blackhole89: You're most likely right. It must be a bitwise thing, but so far I've only encountered FF FF and 02 02. I'll fool around with more bits later today.
Kawa: Haha, yeah. Surprisingly simple alright. Once again I came to only step by. I gotta go again but I'll be back sooner or later. ____________________ oh |
| Naulahauta |
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Red Paragoomba Level: 19 Posts: 53/56 EXP: 30495 Next: 5282 Since: 10-27-09 Last post: 3705 days Last view: 486 days |
Over 1 year bump, ooooh wow.
Well, anyway, I've documented pretty much everything about this game. Well, not everything, but enough to make a functional editor. What's left is still some minor (though a few crucial) things. If anyone has a good, in-depth comprehensive Z80 assembly tutorial, please link me to it. I know 65816 but only because of the amount of tutorials and Geiger's amazing debugger. I've tried to disassemble the game with both, Game Lad and NO$GMB and both give me good results, but I can't understand anything. Well, regardless, here's a few things one should know before diving into the ROM map: -Level data - How levels are built -Block/sprite data - What levels are built from -Demo playback data - What happens after you wait in the title screen for the demo -Door/transition data - What room you go into upon door/teleport And finally, the ROM map. Includes enough information to create a hack. May include some sentences that sound stupid... I'm not that good when it comes to explaining how stuff works, but I tried my best :X If anyone has any questions I'm sure I can answer. Spoiler: If the above link's sprite elaborations look strange, here's another version. ____________________ oh |
| Main - ROM Hacking - Chalvo 55 | New thread | New reply |
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