Request: The Legend of Zelda: Oracle of Ages/Seasons - GBC palette on GBA

[Paar86]

Hi.

There are codes that allow playing the Oracle series on GBC with GBA functionality enabled.

i.e.

Legend of Zelda, The - Oracle of Seasons (USA) (Alan 00X)

Access The Advance Shop On A GameBoy Color
01EA14CF (Gameshark)
CF14:EA (RAW)

Description: RAM Write - Constantly writes 0xEA to the RAM address 0xCF14.

Is it possible to make it other way around so I could play the game on the GBA with GBC functionality enabled (original palette)? Would it work on the real hardware?

Thanks.

[ReyVGM]

What do you mean by "original palette" exactly? The game has the same graphics regardless of the system you use to play it.

Now, if the game looks different on the GBA, that's due to the GBA's screen, not the actual game. Unless the game has enhanced graphics when playing on the GBA? (Although I don't remember the game having that.)

[Paar86]

The Oracle series use two different palettes. One (the original) is set when playing on Gameboy Color. But when you put the games to Gameboy Advance they use slightly brighter palette (probably because the GBA screen is slightly darker) and you can access a hidden shop where you can buy two additional rings.

You can see it here (left is GBC palette, right is GBA palette):



What I'd like to achieve is tell the game it's inserted in a Gameboy Color even though it will be inserted in my Gameboy Advance SP (AGS-101 with backlit screen). So I can enjoy darker, more realistic colors.

[ReyVGM]

Oh you're right. I didn't know it did that.

I assume it must be an easy code to do for a more advanced hacker. It's probably a simple address that turns GBA mode on or off. However, you will probably not have access to the GBA exclusive shop if the game is in GBC mode.

[Paar86]

However, you will probably not have access to the GBA exclusive shop if the game is in GBC mode.

You can always enter the GBA mode, buy the rings and revert back to the GBC mode...

I found this on another website by user Dwedit (http://www.romhacking.net/forum/index.php?topic=16652.0):

"GBA detection works by the initial value of the B register.
The entry point of any GB game is 0x0100. So go there, and see when the code first reads the B register.
Oracle Of Ages is checking bit 0 of the B register at 0159, then carrying out a conditional jump at 015B.
Replace the conditional jump (jr z, xx) 0x28 with an unconditional jump (jr xx) 0x18."

Will that help?

[Mezmorize]

...then carrying out a conditional jump at 015B.
Replace the conditional jump (jr z, xx) 0x28 with an unconditional jump (jr xx) 0x18...

Sounds like that's your code right there 015B?28:18

Have not tested it, but encrypting that to Game Genie makes this code:
181-5BF-4CA

[Paar86]

Thanks! I'll try it right away when I'll get back home from work. Do you think it will work on the real hardware (Game Genie or Gameshark Pro)?

EDIT: I can confirm that the code works, at least in an emulator. But I have one request - could you please convert the code from GG format to Gameshark format?

[Helder]

No way to do that and I have tried to make ASM work in RAM aka Game Shark and it doesn't work.

[Mezmorize]

I don't know if the RAM code works on real hardware, but it appears to in the emulator:



I don't think GameShark can use RAM addresses starting with FF, but I'm not sure.

Edit:
It appears the code indeed does work on real hardware.
http://i.imgur.com/fGHdFcy.jpg
http://i.imgur.com/VuypTjB.jpg

[Paar86]

So is there any way to make the code work on the real hardware apart using flash cards?

[Mezmorize]

I just tested it on a "GB Boy Colour" clone system and a GameShark and the code does work:
01??96FF
??=01 - Darker
??=FF - Lighter

[Paar86]

I assume the first screenshot is the GBC palette on? It's good to see that the Gameshark can process the code. May I ask what version of GS did you use?

By the way, great work. Thank you very much .

[Helder]

I just tested it on a "GB Boy Colour" clone system and a GameShark and the code does work:
01??96FF
??=01 - Darker
??=FF - Lighter

Did you find this code by comparing RAM for changes between the ROM code being on and off or did you trace from that Rom address?

[Mezmorize]

May I ask what version of GS did you use?.

Honestly I don't know the version. It's clear and just says something like "For Game Boy Color and Game Boy Pocket" on it.

Did you find this code by comparing RAM for changes between the ROM code being on and off or did you trace from that Rom address?

I didn't do any RAM searches, I just looked at the ROM code.

[Helder]

I'm thinking this might be a backlight mod and might be portable to other games as well, worth looking into.