Homebrew Full Screen GBA idea.

[The Teej]

Ok, first of all, don't assume I have the best knowledge of the how GBA works on the DS or even how the DS works, but, it's just something I was thinking of.

Now, correct me if I'm wrong, but the way the GBA games are played is that the DS Firmware tells the DS it wants to run a GBA cartridge and puts itself into GBA mode, using the GBA hardware inside the DS. Either that, or the DS downclocks itself. Either way, it's done using hardware, right?

Now, the whole reason why emulation is so hard to do on a lot of platforms is because the hardware is really different, right? But, what happens when the hardware is identical? As you know, the DS can access the GBA slot in real time (with things like the RAM expansion or the rumble pack). So, would it be possible to create an "emulator" that pretty much just recreates the GBA environment, but allows it in full screen?

I figure this is probably complete BS considering if it's this easy and it hasn't been done yet, chances are it can't be done, but I thought I'd throw this around anyway. Worst that's gonna happen is I get laughed at and we all move on, lol.

Your thoughts?

 

[iamwhoiam]

There are two chips in the DS:

Arm7 - used for running GBA in GBA mode. Also used for some DS functioning in DS mode, e.g. touchscreen processing

Arm9 - used for running DS in DS mode.

DS Mode: uses Arm7 for some functioning, and allows access to slot2
GBA Mode: uses Arm7 for GBA processing, switches off NDS hardware, inc slot1

Therefore, the only way to run GBA is emulation. The Arm9 isn't powerful enough to emulate the Arm7. It is powerful enough to just about handle SNES processing. But if we compare SNES to GBA: http://wiki.pocketheaven.com/SNES_Advance ...as you can see, the tech specs are miles off, and basically it's impossible to emulate without better processing.

This has been posted last week, the week before that etc:
http://gbatemp.net/index.php?showtopic=50746


*laughs, moves on* (jokes btw)

 

[The Teej]

Hmm, but the DS can use the Arm 7 fully, right? Then surely we can emulate the GBA using Arm 7 instead of Arm 9? I mean, all we'd be doing is creating software to basically run the games (I mean, we wouldn't have to convert anything via software, it'd be a direct translation).

Hmm, ok, so I just read up on Wikipedia and apparently Arm 7 is used for sound and touch screen while Arm 9 is used for Graphics. So... isn't there a way of splitting up the two (the graphics and audio)? I mean, I know Arm 9 isn't enough to emulate the whole of the gameboy, I understand that, but surely just the graphical aspect can be done, right?

 

[Rayder]

I just wish Ninty would have just had an option, something like how they had for GBA SP's, where older GB/GBC games could be stretched to full screen. Sure, maybe some games would have looked bad that way, but I'm sure many would have been just fine. Besides, if it was just an option, you could always run games that looked bad stretched in normal mode.

 

[iamwhoiam]

Hmm, but the DS can use the Arm 7 fully, right? Then surely we can emulate the GBA using Arm 7 instead of Arm 9? I mean, all we'd be doing is creating software to basically run the games (I mean, we wouldn't have to convert anything via software, it'd be a direct translation).

Hmm, ok, so I just read up on Wikipedia and apparently Arm 7 is used for sound and touch screen while Arm 9 is used for Graphics. So... isn't there a way of splitting up the two (the graphics and audio)? I mean, I know Arm 9 isn't enough to emulate the whole of the gameboy, I understand that, but surely just the graphical aspect can be done, right?

No, when the DS is in NDS mode (slot1 solutions), it uses most of the Arm7 for NDS processing. There isn't enough power available to run GBA on the Arm7, cos most of the Arm7 is in use. Also the hardware in the GBA is basically the same as DS, without the Arm9. It has a single Arm7 and uses all of it for it's processing. What you are talking about is multi threading GBA applications to use Arm7 and Arm9, which to be frank, is silly.

And nope, the Arm9 cannot emulate Arm7. Like I said before last week, and people have said before... Imagine PSX emulators when they first came out for PC. These emulators maxxed out processing powers on PCs, which were 30 times faster than a PSX core (running at 33mhz @ 32bit). The Arm9 can no way emulate Arm7 as it is different architecture. Edit: This is why SNES can be done, cos it runs a measly 3.5mhz @ 16bit.

Maybe a modchip could be used to turn off the Arm7 DS functions and use it as GBA. But a) you'd have to open up the DS lite and install it and b) 3in1 expansion pack costs less than a tenner, so why bother?

End of the day, same conclusion: can't be done.

 

[iamwhoiam]

Oh and secondly, running GBA from slot1 cannot be done because the interface isn't fast enough.

GBA games require very very quick access times, due to the way it's designed to run. This makes putting GBA on removable flash media (microsd etc) impossible. The slot1 interface isn't designed for GBA access.

Some people argue you could dump the GBA rom into the DS's memory, but the DS's memory is only 4mb in size.

 

[reaperman@home]

maybe I'm just crazy, but wouldn't the gba games look pretty bad full screen? going up to the slightly higher res of the ds would be just about enough to have everything looking pretty swimmy. The aspect ratio would also be slightly wrong.

 

[archagon]

Seriously, why are you people so obsessed with stretching?
The GBA screen isn't THAT small. Please -- get over it, or get a GBA SP!
Do the black bars really bother you that much?

(No offense to anyone. I just think that having your games look like crap is too large a price to pay for a slightly bigger screen.)

 

[The Teej]

Seriously, why are you people so obsessed with stretching?
The GBA screen isn't THAT small. Please -- get over it, or get a GBA SP!
Do the black bars really bother you that much?

(No offense to anyone. I just think that having your games look like crap is too large a price to pay for a slightly bigger screen.)

It's big enough and I have a GBA SP, but the SP is practically pitch black compared to the DS Lite.

 

[OrR]

Well, the improved GBA SP should be about the same.

 

[Veho]

Well, the improved GBA SP should be about the same.

I'm given to understand only the "special edition" GBA have the new and improved backlit screen. Meaning, not only would I have to pay extra for the better screen (even when buying a used console), I'd also have to pay -extra- extra because it's a collectors' item, limited edition, Pokemon Pikachu GBA. Or something.

 

[reaperman@home]

the custom work or modding being talked about in here would cost far more than a backlit sp. which isn't really "special edition" just low demand.

the ds has a resolution which would not be very compatible with stretched gba. I'm sure that if it looked halfway decent, nintendo would have given us the option themselves. But you'd have some kind of flicker scaling, or some kind of doubling up of certain vertical and horizontal rows.

 

[Xenophobe]

I think it would be alot of work for something that wouldn't be that great.

You could always just use that GBA background hack if you don't want to see the black border.

 

[xenaro28]

it would be very ugly thats all i got to say.

 

[shakirmoledina]

No one is gonna release the modchip for playing gba games i dont think anyone wants to compete with the 3 in 1 expansion

 

[OSW]

Stretching GBA screen is not nice visually.

 

[funem]

GBA Micro is awsome for GBA games, and the screen is nearly as good ( if not on par ) with the DS Lite

 

[reaperman@home]

GBA Micro is awsome for GBA games, and the screen is nearly as good ( if not on par ) with the DS Lite

while I love my GBM above all other handhelds, and am totally with you on that, the topic was started by somebody who thought the ds screen with the borders was too small. I just don't think he's going to see eye to eye with us on the awesome quality of our postage stamp screen.