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Pokémon Discussion

Pokémon Gold and Silver VRAM question - Page 1

Pokémon Gold and Silver VRAM question

Posted by: Torchickens
Date: 2015-12-15 15:41:05
I'm wondering if any addresses in Pokémon Gold and Silver's VRAM are unused.

If you modify the bank 0 VRAM, it is possible to get a chance of manipulating what Celebi becomes when traded over from Generation II to Generation I (Háčky documented that what FB and FD become in Generation I is hard to predict and depend on the memory). On my save file, I changed 0:803A in VRAM to FB and successfully got the conversion as Mew (my conversion is often Mankey), but this address was overwritten after entering the Cable Club Time Capsule.

Another option may be modifying the SRAM; if cheat searcher was correct in saying that there are no FB in the VRAM, but there are multiple SRAM banks and I'm not certain which one the game would get data from(?)

Thanks in advance.

Re: Pokémon Gold and Silver VRAM question

Posted by: Háčky
Date: 2015-12-15 21:30:49
The VRAM area $800087FF is normally used for overworld sprites. Only tiles $0023 ($8000823F) are used for sprites on the Pokémon Center second floor. The remaining tiles will be left over from the last areas visitedusually some sprites from the first floor, and the rest from the city you entered the Pokémon Center from.

If the game is started fresh from a save on the second floor of the Pokémon Center, this area of VRAM will be filled with the Ho-Oh or Lugia graphic from the title screen. In Gold, Ho-Ohs sprite places an $FD byte at $82AA, which should result in that index number being converted to Magikarp through the Time Capsule, but it doesnt contain an $FB byte. In Silver, Lugias sprite doesnt contain either $FB or $FD.

During a trade, that area of VRAM is used to store the sprite of the Pokémon being traded. After each trade, the party data is re-converted and re-transmitted (during the PLEASE WAIT! screen), so the conversion of $FB and $FD may be affected by the last Pokémon that was traded.

If the search reaches SRAM addresses, it should normally read all $FF bytes because SRAM access is locked, and thus the search would continue into WRAM. (However, as I discovered while investigating Crystals item $00, that behavior is erratic on a Game Boy Advance. It may be possible for $FB to be found in SRAM, but it would be impossible to predict where.)

Re: Pokémon Gold and Silver VRAM question

Posted by: Torchickens
Date: 2015-12-16 19:07:12
Thanks Háčky!