Why does GBA games not work on Slot 1 cards?

[Dragonic]

Yes, I really wonder! Why?? I hope this is'nt against the rules, now when I'm talking about this, tell me if it is then. But, back to the topic... Why does it not work?? I thought it was simple to Emulate GBA on a NDS! Because the NDS can run normal GBA cartridges! Is it not possible to make a GBa emulator that "imagines" that it is a GBA game in Slot 2?? Well, I'm really not an expert, but I was only thinking, and I'm happy for answers...

btw. I think it's a loads of persons that've done it before me, but I contacted R4DS and asked them about GBA support and the next firmware update. I'm now waiting for an answer.

[DimensionT]

A GBA emulator wouldn't be very feasable... It's quite a feat that the DS can emulate the SNES, but the GBA is more powerful. Plus, there's not much point to it. It'd be like emulating the Gamecube on the Wii.

A hack to make it send the GBA data from slot1 cards to slot2 might be possible though. After all, slot2 devices can play DS games.

[Dragonic]

yes, it's just that I mean! It should be really nice if someone tried to make a emulator that sends the data from slot 1 to slot 2.

[ButterBeer121]

I've heard that it is currently impossible to do that. People are still trying though.

[Gorgonek]

Isn't it about additiona ram on those slot2 devices that can be used for the GBA roms?

[DimensionT]

I'm pretty sure that's just so it can load the GBA rom into ram, so there's no slowdown and stuff. It should be possible to stream them like they do with DS games though.

[DanTheManMS]

GBA games are directly addressed, that is, most data is read directly from the cartridge rather than from RAM. The DS slot is not capable of this method, as it loads chunks of the game into RAM, where it is the run. DimensionT is right in that DS games are streamed from the card in a sense, but GBA games function differently. So you can't run GBA games directly from slot-1.

You can't just use the ARM7 to emulate/simulate the GBA because it functions entirely differently in DS mode than it does in GBA mode. While in GBA mode it handles everything, in DS mode it only handles some buttons, touchscreen, wifi, and power management (among other functions of course). There are functions the ARM7 can handle in GBA mode that are inaccessible in DS mode. So therefore, you can't run GBA games in DS mode at all.

As a result, one must conclude that GBA games must run in GBA mode on the DS. Then the question comes up of where you're going to store the data for the GBA to use. You can't just load up the DS's 4 MB of RAM with GBA game data and then boot into GBA mode, as the DS's RAM is cleared and becomes inaccessible when you go into GBA mode. You can't just load up the GBA's 256 KB of RAM with a multiboot homebrew demo and then boot into GBA mode because the GBA's RAM is cleared by the GBA's BIOS when it runs. So therefore, it's not possible to store the game into on-board RAM before execution.

The only other way to get a GBA game working on the DS without a slot-2 device would be an emulator, and nobody is going to write a software renderer that would be slow and buggy when the DS already contains 100% accurate hardware emulation as it is. It would be a waste of time.

[Gorgonek]

So the only way is buying slot-2 card reader. Which is the cheapest and runs GBA games correctly on DS?

[kickasspats]

umm http://dealextreme.com/details.dx/sku.2967
i heard this is the best one, its 20$ on dealextreme

[::Xraxa, plz:.]

GBA games are directly addressed, that is, most data is read directly from the cartridge rather than from RAM. The DS slot is not capable of this method, as it loads chunks of the game into RAM, where it is the run. DimensionT is right in that DS games are streamed from the card in a sense, but GBA games function differently. So you can't run GBA games directly from slot-1.

You can't just use the ARM7 to emulate/simulate the GBA because it functions entirely differently in DS mode than it does in GBA mode. While in GBA mode it handles everything, in DS mode it only handles some buttons, touchscreen, wifi, and power management (among other functions of course). There are functions the ARM7 can handle in GBA mode that are inaccessible in DS mode. So therefore, you can't run GBA games in DS mode at all.

As a result, one must conclude that GBA games must run in GBA mode on the DS. Then the question comes up of where you're going to store the data for the GBA to use. You can't just load up the DS's 4 MB of RAM with GBA game data and then boot into GBA mode, as the DS's RAM is cleared and becomes inaccessible when you go into GBA mode. You can't just load up the GBA's 256 KB of RAM with a multiboot homebrew demo and then boot into DS mode because the GBA's RAM is cleared by the GBA's BIOS when it runs. So therefore, it's not possible to store the game into on-board RAM before execution.

The only other way to get a GBA game working on the DS without a slot-2 device would be an emulator, and nobody is going to write a software renderer that would be slow and buggy when the DS already contains 100% accurate hardware emulation as it is. It would be a waste of time.

Thanks for the explaniation, helped me a good bit.