GBA program that enters GBC mode.

[wraggster]

New from DWedit: (http://www.dwedit.org/dwedit_board/viewtopic.php?id=339)

Here's a little GBA program that enters GBC mode.
Newer version! Press A to enter GBC mode!
Includes source code.

Download Here (http://www.dwedit.org/dwedit_board/attachment.php?item=127)

[DanTheManMS]

Just a few notes from the PocketHeaven thread this originated from:
1. Only works on GBA, GBA SP, and GBM. Not the DS Phat or DS Lite.
2. On a GBA or GBA SP you'll hear the sound but you won't get any video. On a GBM you'll get both sound and video
3. Modifying a GBC cartridge to not press the internal switch and then running this program doesn't work, so you cannot use it to run GBC games on a GBM. That was the intention, but it didn't work.

Interestingly enough, the entire reason this came about was from a bug in Goomba Color's saving system that crashed GBM systems into showing the GBC BIOS.

[otto_xd]

It may be useful tu run gbc games in gba & gbaSP with a flash card, no?

Sorry for my bad english

[mcdougall57]

i have a gbm and a flash cart can i use this to run gbc games?

[Eyedunno]

i have a gbm and a flash cart can i use this to run gbc games?
Wow, yeah, I want to know this too. I thought GBM was also incapable of playing GBC games.

[acn010]

sorry but its useless for me.

[Hypershell]

i have a gbm and a flash cart can i use this to run gbc games?I suggested that a while back on PocketHeaven (this program was actually done in January), and this is where the conversation went:

Dwedit: As far as I know, the GBC and GBA use a different protocol on the cartridge bus. You'd need a card which would perform the reads and writes the same way as a GBC cartridge.
tepples: True, but the GBC protocol is similar to the GBA SRAM protocol, with about three or four enable lines switched around. I'd bet that's how the Flash2Advance GB Bridge got away with it. If someone's serious about this, I'd recommend taking a logic analyzer, logging the startup sequence of a GBC, and logging the same parts of the startup sequence of a micro that has crashed into GBC mode.

That was written before Dwedit released the program, hence the "crash" part.

As far as I know it hasn't gone anywhere from there. The only attempts at running a GBC game that I'm aware of were cutting legitimate cartridges, which failed. I'm not sure if anyone has yet attempted this with a flash card or not.

[DanTheManMS]

If you've got a GBM and a flash cart, just use Goomba Color to emulate the GBC games. This program, while interesting, doesn't accomplish too much.

[mcdougall57]

goomba? do save files work now? last version i tried you couldnt save your games on it

[DanTheManMS]

I don't recall there ever being a version you couldn't save in...

Savestates are broken in Goomba Color, but in-game saving still works.

[mcdougall57]

i gave it another go and it works fantastically :) here i come zelda links awakening

[Hypershell]

If you've got a GBM and a flash cart, just use Goomba Color to emulate the GBC games. This program, while interesting, doesn't accomplish too much.It's true that the program does jack, but it's the concept that's so tantalizing. The reason tapping into the GBM's Z80 is such a big deal is that the GBA is not powerful enough to emulate the Z80 double speed mode properly, which results in Goomba Color slowing down in several games. Finding the ideal switch between Full and Timers mode helps a lot, but it's still not perfect. And according to Dwedit, it never will be so long as it stays on GBA. Which leaves GBM users up the creek on the higher-end GBC games (not that Goomba Color isn't anything short of amazing; the fact that it came as far as it did boggles my mind).

On the other hand, I always saw GBC emulation as being more relevant to the DS (which this program obviously doesn't work on). If anyone after GBM's release wanted GBC games that bad, they should have gotten a backlit SP instead (as in AGS-101, not AGS-001), and saved a few bucks while they were at it.

[DanTheManMS]

I agree, the idea is tantalizing, but it appears that the idea's been given up on for now. Here are a few posts from the PocketHeaven thread you may find interesting:


When you have a GBC game in a GBA, it first boots in GBA mode, then the gba looks to see whether you have a GBC cartridge inside, then boots GBC mode.

Or at least, in theory, this is supposed to happen. However - If it boots in GBA mode, sees that a GBC cartridge is inserted, and does a soft switch to GBC mode, it will do a fade animation before entering GBC mode. The fade animation does not actually happen, so therefore a real GBA never uses a software switch to GBC mode.

I read somewhere (I'll add the link if I figure out where) that the original creator of the GBA attempted to identify GBC cartridges in software mode, but could never make it work. He found no way to use the GBA's 3v inputs to determine when a 5v GBC cartridge was inserted, and rather than risking frying a GBA cart that didn't have proper contact, he elected to implement the hardware switch.

Since he was so reluctant (according to the article) to use a hardware switch, it makes sense that he worked on a software switch for so long that there wasn't time to remove it completely from the BIOS when the GBA shipped. (And that's a pretty long time, seeing as the GBA was developed at about the same time as the GBC, but it was held back not to impede GBC sales.)

Just my $0.02
trlkly