Homebrew Why the DS can't emulate GBA

[epicCreations.or]

Hello there. I'm a dreamer. I dream big. I've seen many posts saying that a DS couldn't handle GBA emulation or hypervising, but I'd personally like to know all of the exact reasons it could not work.

So, what are the exact reasons the DS could not hypervise/emulate GBA on its own? What are the processing differences, access methods, etc.

-epic Creations

 

[` regret .]

I'm not sure but I think its something to do with not having enough RAM. People also say something about SRAM but i'm not sure wth that is. ):

 

[Tac 21]

not enough memory. PSP could do it no problem.

 

[DeMoN]

Your topic title states, "Why the DS can't emulate DS."

But keep in mind that some flash carts (iPlayer, Supercard 2) can emulate the GBA via slot-1 due to the extra RAM or whatever that they have.

 

[Mike Hawk]

a better question is : Why?

 

[koji2009]

The simple reason is that the DS card slot is not as fast as the GBA cart. The only way to get around this, would be to load up a GBA rom into ram... of which the DS only has 4MB. Smaller than practically every GBA rom.

The only solutions are to use some sort of ram add-on or use the DSi's extra ram which is currently unavailable. If you use a ram add-on on slot-2 in normal DSes you can play GBA games fine, but if you're doing that there is no reason to emulate since those DSes can run GBA games natively.


Understand, GBA carts were relatively expensive... costing as much as 50% of the retail price of a game... meaning companies made very little actual money from GBA games. These games had to be on fast carts because the GBA had very little ram (256k). The GBA game carts were so fast, they could ran most of the game code straight from the cart itself, versus the DS which has to transfer most data to ram BEFORE execution.

By the time the DS came out, ram was much cheaper... And instead of paying for extremely expensive cartridges that ate into everyone's sales, Nintendo moved to a much slower read medium (which is why some DS games actually have load screens like disc based systems where GBA games never did).

 

[epicCreations.or]

I'm not sure but I think its something to do with not having enough RAM. People also say something about SRAM but i'm not sure wth that is. ):

I don't think SRAM is related

Your topic title states, "Why the DS can't emulate DS."

But keep in mind that some flash carts (iPlayer, Supercard 2) can emulate the GBA via slot-1 due to the extra RAM or whatever that they have.
Damn. Knew I must have done something wrong when posting.

Yeah, I knew about those, but I meant natively on a flashcart already out (like an AceKard 2i

)

The simple reason is that the DS card slot is not as fast as the GBA cart. The only way to get around this, would be to load up a GBA rom into ram... of which the DS only has 4MB. Smaller than practically every GBA rom.

Would you happen to know how big the access speed difference is? That would be a helpful indicator of what could be expected if this were possible at this point in time.

QUOTE

The only solutions are to use some sort of ram add-on or use the DSi's extra ram which is currently unavailable. If you use a ram add-on on slot-2 in normal DSes you can play GBA games fine, but if you're doing that there is no reason to emulate since those DSes can run GBA games natively.

In that case, I should focus on hacking the DSi, eh? *sets off to google*

Thanks for the answers, to those of you who are helpful.

 

[fgghjjkll]

Like others said. The DS Cart is NOT fast enough. With only 4mb ram for a hypervisor, you would have to swap out data pretty fast...

 

[epicCreations.or]

Thanks for repeating known information

I would like to know the speed differences, since it's already been established that the DS cart is slower than the GBA cart.

 

[gameguy95]

As has been said about 5 times so far: not even close to having enough RAM

 

[epicCreations.or]

Ignoring that... You don't seem to understand what I'm getting at... I'm thinking of building a GBA emulator for the DS, not for actual use, but rather just to prove it could be done. I don't actually care if it's slower or anything like that. I just want to know if there are specific barriers that would completely stop me from emulating the GBA.

 

[mcbey]

If youre unable to grasp the concept about why one type of memory is slow than the other, I highly doubt you would be able to build an emulator for anything.

 

[Advi]

It would be extremely slow and painful to play............but it could probably be done.
Thing is, why build an emulator when you can't play it pleasurably? It's much more fun to just buy a Slot-2 cart and use that to play the game.

 

[Gore]

He already said he just wants to do it to do it, asking why isn't helping and neither is telling him he can't, if you're going to say he can't tell him why it is completely impossible to create an even unplayable emulator..
Whether he is capable or not doesn't change his questions

 

[DeltaBurnt]

As has been said about 5 times so far: not even close to having enough RAM

Please don't just restate what 5 other people said just to up your post count, it's not really helping.

Ignoring that... You don't seem to understand what I'm getting at... I'm thinking of building a GBA emulator for the DS, not for actual use, but rather just to prove it could be done. I don't actually care if it's slower or anything like that. I just want to know if there are specific barriers that would completely stop me from emulating the GBA.

You could technically have the emulator play games under 4 MB, or have it automatically load the new required data from the rom into RAM everytime it needs new data. So it'll store as much as it can in RAM, and once it needs newer information it could pause and have a loading screen. Or possibly have it replace old data with new data constantly, but you may not be able to accomplish that with the DS's processor...

That's another thing you need to worry about with emulation. Not only do you need enough RAM but a good enough processor (the old rule of thumb is that you need atleast a 7x faster processor than what the original product had for emulation but that's not always the case).

QUOTE(Advice Dog @ Mar 15 2010, 11:11 PM)

It would be extremely slow and painful to play............but it could probably be done.
Thing is, why build an emulator when you can't play it pleasurably? It's much more fun to just buy a Slot-2 cart and use that to play the game.

Well think of it like this, someone buys a flashcart for piracy 99% of the time. So if they already spent a fortune of 20 bucks on the flashcart, do you think a pirate would spend another 10 bucks for a EZ Flash 3-in-1?

 

[stuffnflufff]

Technically speaking you would literally need to go into the code and write a statement telling the code to refresh after 4MB of usage (kind of like a Disc uses the data stored on the disc from a different spot constantly) meaning youd have to make the emulator THINK its a disc iso. This way it could grab info and put it back on the fly. It SHOULD be possible if you do it that way. Just cant think of exactly how youd do it (first year uni computer science has made me think of theories, just dont know if they work lol)

 

[Saddamsdevil]

DS2 will probably be released before you finish this though, and if it does turn out to work, I don't think people who bought ds2's will be very happy

 

[Jamstruth]

Surprised nobody's mentioned specs. DS has 90MHz of power while the GBA has about 33MHz I don't think the power difference is enough for a decent emulator (the iPlayer has its own processor of 400MHz so the cart is actually more powerful than a DS)
Also on top of only having 4MB of RAM you must reserve say 1MB for the emulator's programming to run in (this is why JenesisDS can only run ROMs

 

[Llama Riot]

Throughout the GBA's lifetime people constanly flamed and trolled users inquiring about the possibility of emulating SNES on the GBA. They all said it was impossible: This proved them all wrong. So please stop saying that something is impossible when it cleary is not. Difficult? Unlikely? Yes, seeing as you can just get a slot 2 cart, but certainly not impossible.

 

[heartgold]

If only we had access to dsi mode, it would turn the impossible to less likely, huh?

Getting data to be refreshed constantly on a standard DS sounds like the only option of playing an actual gba rom, however how will one get around this, seems like really hard work and may turn out to be impossible.