Passme

[Robert]

I've been wondering what the term "passme" was about, and have uncovered an explanation of it. For those who are interested, here it is, courtesy of http://www.hungrydeveloper.com

 

Those of you who have been following the attempts at running code on Nintendo's new hand held console, named the DS, will have probably heard of the idea behind the pass through.

 

If not, to understand the pass through you need a little background information on the DS and its predecessor, the Game Boy Advance (GBA). Over the past few years, home brew development for the GBA has revolved mostly around the flash cartridge, a writable game cartridge that allows developers to run their own code on the GBA. These cartridges became widely available due to the fact they were also very handy for software piracy, which while a shame for the licensed developers themselves it certainly helped to drive down the costs and raise the availability for home brew developers.

 

Now, the DS can also play GBA games and has two slots, one for the GBA cartridge and one for the DS cartridge. When playing GBA games, the DS runs in GBA mode, allowing only the features of the GBA. When playing DS games, the DS runs in DS mode, allowing its full capabilities to be exploited. Using flash cartridges for the GBA with the DS is generally not a problem, but alone a GBA flash card can only be used to run GBA code in GBA mode, with none of the extra features the DS has.

 

While the ideal answer would be to produce flash cartridges for the DS to run new code, there is several problems. These problems range from legality to cost effectiveness, and while it is assumed they will be overcome at some point in the future it may be quite some time, and then may be stamped out of production by lawyers.

 

The solution is very clever indeed. A pass through which plugs into the DS cartridge slot and tells the DS to load code from the GBA slot, where a GBA flash card is loaded with DS data. This is a very simplistic view of the idea, and to get a better sense of it, browse these points.

 

The DS runs an ARM7 and an ARM9 CPU.

DS games contain a header with code entry points for both CPU's.

In DS mode, the DS has the GBA cartridge mapped to an area of memory.

 

So what the pass through does is sit between the DS and a DS cartridge, and modifies the header as it goes to the DS, setting the entry point for the ARM7 code to the GBA cartridge, which then runs in DS mode and can take control of the system. The advantages of this system are that it is virtually useless for piracy, and it doesn't appear to break any laws.

 

This week, a big development in the DS pass through system has occurred, with Natrium42's "PassMe" pass through being built and tested by Lynx.

 

More information on the PassMe can be found at http://www.dslinux.org/blogs/natrium42/ and information and photos of Lynx's adventures with the device can be found at http://www.dspassme.com/.

 

I contacted Lynx for comment, and he gave this quote:

I'd like to thank Natrium42 for giving me the opportunity to be a part of PassMe.

He also insisted that Natrium42 get full credit for the device, and that there is plans in the works for manufacturing and selling the PassMe. Natrium42 has not been contacted for comment.

 

Some recent demos include a PassMe version. These are the roms that end with a ".ds.gba" extension. The latest version of iDeaS, 1.0.0.2, can run these demos, as long as the extension of "pme" is added.

[Federelli]

Passthrough is the "formal" word for it .

[Two9A]

The passthrough is the generic name for the device; both natrium and DF have built passthrough devices, for example. It is only natrium's design that is called the PassMe, since it has been named as such.