(Request) Zelda Oracle of Ages/Seasons - Disabling color palette modification on GBA

[Paar86]

Hi. There is this functionality in The Legend of Zelda: Oracle of Ages/Seasons where the game can check if it is played on a GBA and if true, it will change it's palette to lighter tones and open a special shop with exclusive rings.

The check is at 0x0159 and is followed by conditional jump. Changing the jump from conditional to unconditional partially fixes the issue - the palette is not modified but the shop remains closed.

I have tried to locate the code that changes the palette colors but was unsuccessful as my ASM hacking skill are rather low.

Would it be possible for some of you to try and locate it? So if the games are played on GBA the palette remains the same but the special ring shop stays opened?

[nensondubois]

Legend of Zelda - Oracle of Ages.gbc

Force GBA Mode
FE1-55F-E6A

Force CGB Mode
FE1-5EF-195

Legend of Zelda - Oracle of Seasons.gbc

Force GBA Mode
FE1-55F-E6A

Force CGB Mode
FE1-5EF-195

[Paar86]

I would like to take it a step further. How about not forcing anything, just turning off the palette change in the GBA mode? Preferably as a ROM hack not a cheat.

The only thing that is different when switching to GBA mode is that when checking the B register the value FF is stored on adrress 0xFF96. In GBC mode the value 01 is stored there. Why does that matter I don't know.

[nensondubois]

I'm in a rush right now and won't be on for a few days but I think this solves your problem directly. I haven't tested if this leaves the other effects GBA alone detected like you want but I think this code only disables the palette. (untested due to not having a proper save for the ring shop)

Oracle of Ages

Disable GBA Palette
E00-3BB-2A9

And for the hell of it
Make DMG/SGB Compatible
E09-8AA-2A9

Oracle of Seasons

Disable GBA Palette
E00-3BB-2A9

Make DMG/SGB Compatible
E00-00B-2A9

[nensondubois]

Seasons

Advance Shop is closed
E01-959-2A9

Ages
Advance Shop is closed
E05-339-2A9

If you are planning on using the codes with GBA/CGB hardware you will need a Codebreaker cheat device.

[Paar86]

I have tried the first code (disabling GBA palette) and even though the background tiles had right dark colors, the link sprite had modified light colors. Unfortunately when using this code the GBA shop remains closed .

EDIT: Your code for Advance Shop works. I'll try to work with that.

EDIT2: No good. When using the codes I can open the shop even in the GBC mode. Is it possible to modify it so the shop opens only in the GBA mode while retaining the original darker palette?

[Paar86]

Ok, I think I have found what I wanted. With this patch you can play the game with the GBC palette on GBA and with the Advance Shop opened but when you play it on GBC the Advance Shop will be closed (as intended by the developers).

The Legend of Zelda: Oracle of Seasons/Ages (U)

GBC palette + original Advance Shop behaviour
FC03B -> 3E 01

[nensondubois]

Ok, I think I have found what I wanted. With this patch you can play the game with the GBC palette on GBA and with the Advance Shop opened but when you play it on GBC the Advance Shop will be closed (as intended by the developers).

The Legend of Zelda: Oracle of Seasons/Ages (U)

GBC palette + original Advance Shop behaviour
FC03B -> 3E 01

Looks like that solved your issue. Sorry I couldn't get to it in time.

[Paar86]

Thank you anyway for your help .

Funny thing is that it took me several days to make this simple patch (in fact this is my first functional hack ever). I'm sure you would have created it in a matter of few minutes.

The patch is not thoroughly tested but it should work.