Stupid idea about gba multiplayer in a ds

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Bush
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Stupid idea about gba multiplayer in a ds

Post by Bush » Mon Sep 13, 2010 10:25 pm

As we are all aware, the ds lacks the ext. Port found on the GBA. this means no link cables or assescories are compatible. However, I have hope. The GBA not only has its own processor and CPU, but also has the components to allow GB and GBC games to work. Im pretty sure (i swear u read this) that another processor and clock crystal is used for that feature. This is because the GBA and GBC have different architecture. Also, the GBA and DS have completely different architecture. I am certain that the DS does not emulate the GBA, but it has a secondary CPU or something to handle the GBA processes. Now here's my hunch. This processor or "GBAOC", whatever it may be, might be the carbon copy of the GBA's chipset or a differrnt one. If it is identical, it should have (but may not) have unused pins for the ext. lines. Another scenario might be that the GBA processes are handled within the DS's main chipset, so that the GBA may be powered by some proccesor that also runs DS functions. I realize this is a huge shot in the dark, especially due to the fact that the DS has seversl revisions, and two models with GBA features, and screens with different resolutions, sizes, driver boards, and pinouts. I'm just ranting here in the hopes that someone may be able to shed some more light on this severely doubtful subject. Once again, this is all speculation, so no trolls please. I think one big step towards fifuring this out would be some pictures of the original DS internals; if anyone can provide them, youre a big help:)

Edit: according to wikipedia, the secondary CPU handles the GBA function of the DS. This most likely means this is not possible.

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nitro2k01
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Re: Stupid idea about gba multiplayer in a ds

Post by nitro2k01 » Tue Sep 14, 2010 5:05 pm

Bush wrote:Im pretty sure (i swear u read this) that another processor and clock crystal is used for that feature. This is because the GBA and GBC have different architecture.
There are two CPUs in the same chip, and they're using the same clock crystal. Even tohugh they're in the same chip, they're very different.
Bush wrote:Also, the GBA and DS have completely different architecture. I am certain that the DS does not emulate the GBA, but it has a secondary CPU or something to handle the GBA processes.
(My emphasis)
Actually, no. The GBA CPU, called the ARM7, is an integral part of the DS's normal functioning. When used in DS mode, it still has the same instruction set, etc, but is clocked at a higher frequency. (16 MHz in GBA mode, 33 MHz in DS mode.) In DS mode, it's mostly used for audio playback.
Bush wrote:If it is identical, it should have (but may not) have unused pins for the ext. lines.
The topic has already been researched by Martin Korth, who also made the no$gba and no$gmb emulators. (As well the lesser known no$nes, no$c64, no$cpc, no$msx, no$zx81 and no$x51 emulators, but I digress.)

http://nocash.emubase.de/gbatek.htm#dsabsentlinkport" onclick="window.open(this.href);return false;

Warning: 1 MB HTML file. 56k'ers beware! For this reason, here's the relevant portion quoted:
DS Absent Link Port
The DS doesn't have a Serial Link Port Socket, however, internally, the NDS7 contains the complete set of Serial I/O Ports, as contained in the GBA: GBA Communication Ports

In GBA mode, the ports are working as on real GBA (as when no cable is connected). In NDS mode, the ports are even containing some additional bits:

(Here be a chart of the IO port functionality.)

Not sure if these ports really exist in the release-version, or if it's been prototype stuff?

DS Serial Port
The SI line is labeled "INT" on the NDS mainboard, it is connected to Pin 1 of the RTC chip (ie. the /INT interrupt pin).
I have no idea where to find SO, SC, and SD. I've written a test proggy that pulsed all four RCNT bits - but all I could find was the SI signal. However, the BIOS contains some code that uses SIO normal mode transfers (for the debug version), so at least SI, SO, SC should exist...?
So, no, you're out of luck.
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ASM Retro <- Gameboy Classic Backlight

Being the sadistic bastard I am, I have covered Frog's left eye with a Santa hat.

Last edited by nitro2k01 tomorrow, 1:48 pm; edited 1 time in total

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Bush
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Re: Stupid idea about gba multiplayer in a ds

Post by Bush » Tue Sep 14, 2010 6:31 pm

So basically, it could be possible, but we cant access 3 necessary pins. Thanks!

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bentendo64
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Re: Stupid idea about gba multiplayer in a ds

Post by bentendo64 » Wed Sep 15, 2010 8:19 pm

Here is my idea on the subject of GBC on NDS: (sorry, I tped this up, and then realized that it wasn't the topic, but still somewhat relivant)
A friend and I were talking about this at school one day, and he said that he was able to access GBC mode while in DS mode. This The only problem was that he wasn't able to modify the GBA cart slot so the GBC cart didn't fit.
this might help....
http://bentendo64.co.cc/" onclick="window.open(this.href);return false;
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Bush
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Re: Stupid idea about gba multiplayer in a ds

Post by Bush » Wed Sep 15, 2010 8:27 pm

Really? I've seen someone modify a GB cart to fit in and it wouldn't play.

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nitro2k01
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Re: Stupid idea about gba multiplayer in a ds

Post by nitro2k01 » Thu Sep 16, 2010 6:28 am

bentendo64 wrote:Here is my idea on the subject of GBC on NDS: (sorry, I tped this up, and then realized that it wasn't the topic, but still somewhat relivant)
A friend and I were talking about this at school one day, and he said that he was able to access GBC mode while in DS mode. This The only problem was that he wasn't able to modify the GBA cart slot so the GBC cart didn't fit.
this might help....
That's bogus. The GBC mode doesn't exist anymore on the DS. I have confirmed this myself. It does exist on GB micro, but is useless there.

See this http://nocash.emubase.de/gbatek.htm#lcdiodisplaycontrol" onclick="window.open(this.href);return false; (Warning 1 MB HTML file! 56k GTFO!)

By setting bit 3 in the DISPCNT IO register, you can manually enter GBC mode. This works fine on GBA, although it might damage any GBA cartridge inserted when the command is issued. It works on GB micro, but the mode is useless. (I don't think you can make it work, even with the right voltage conversions etc.) It does not work on DS; setting this bit simply does nothing.
My blog
ASM Retro <- Gameboy Classic Backlight

Being the sadistic bastard I am, I have covered Frog's left eye with a Santa hat.

Last edited by nitro2k01 tomorrow, 1:48 pm; edited 1 time in total

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