GBA Enhanced Game Boy Color games

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SysopGrace
Posts: 9
Joined: 10 Apr 2016 18:41

GBA Enhanced Game Boy Color games

Post by SysopGrace » 01 Mar 2020 06:11

Today I came across some articles about GBC/CGB games that are designed to do some different things when played on real GBA hardware. There does not appear to be any authoritative list but the following 4 are the most frequently cited:

Legend of Zelda, The - Oracle of Ages
Legend of Zelda, The - Oracle of Seasons
Shantae
Wendy - Every Witch Way


They usually have a different color palette, more animations, a few extra items in game or more levels to play.

I searched for more but haven't found anything very concrete and I was wondering if anyone here knew of a way to detect if a GBC game will specifically do something different if it detects that it is running on GBA hardware.


The following website has documentation regarding the way the games detect which device they are running on, specifically under the "CGB Registers" chapter.

https://web.archive.org/web/20140410105 ... andocs.htm


If anyone would be able to figure out a method for determining which games are GBA-enhanced I think it would make for a lovely flag/filter in the dats.

Hiccup
Datter
Posts: 784
Joined: 09 Oct 2015 11:29

Re: GBA Enhanced Game Boy Color games

Post by Hiccup » 01 Mar 2020 12:28

Here's the current link for pandocs, but I don't think its anymore up-to-date (according to the date at the top of the document, at least).

I think this would be a matter of determining the compiled code that would be used to detect this (and there might be more than one way to do it) and then searching for that sequence of bytes in a GB/GBC fullset. There'll be others here who have better knowledge about GB code...

Screwtape
Posts: 29
Joined: 29 Aug 2017 08:46

Re: GBA Enhanced Game Boy Color games

Post by Screwtape » 06 Mar 2020 04:14

I posted a link to this thread in byuu's discord, and Revenant (the maintainer of bsnes-plus) had a poke around:

Code: Select all

21:51:41.31 d:\games\roms\gbroms
>bgrep "a7 fe 11 3e 00 20 06" .
./Network Boukenki Bugsite - Alpha Version (Japan).gbc: 00000150
./Network Boukenki Bugsite - Beta Version (Japan).gbc: 00000150
./Sabrina - The Animated Series - Spooked! (USA, Europe).gbc: 0000396e
./Shantae (USA).gbc: 00003973
./Wendy - Every Witch Way (USA, Europe).gbc: 0000396e

>bgrep "fe 11 3e 00 20 07" .
./Legend of Zelda, The - Oracle of Ages (Europe) (En,Fr,De,Es,It).gbc: 00000152
./Legend of Zelda, The - Oracle of Ages (USA).gbc: 00000152
./Legend of Zelda, The - Oracle of Seasons (Europe) (En,Fr,De,Es,It).gbc: 00000152
./Legend of Zelda, The - Oracle of Seasons (USA).gbc: 00000152
./Zelda no Densetsu - Fushigi no Kinomi - Daichi no Shou (Japan).gbc: 00000152
./Zelda no Densetsu - Fushigi no Kinomi - Jikuu no Shou (Japan).gbc: 00000152
At least there's a few more potential candidates there.

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