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Hardware > Game Wallet (CF/SM card reader): huge potential?

#20615 - Helllo - Thu May 13, 2004 7:58 pm

Hi,

I've been reading about the Game Wallet, which is basically a CompactFlash or SmartMedia card reader that plugs into the GBA's link port.

The Game Wallet sends the b@@t_gb@.mb file as a multiboot image to the GBA. This supplied .mb file allows you to copy ROM images stored on the memory card to a (flash2advance brand) flash cartridge in the GBA's cart slot. (The firmware for the microcontroller in the Game Wallet is also read off the card.)

So you don't need a Windows computer, or a USB interface; you can put a lot of ROM images onto a CF or SM card and use them without further access to a computer.

Has anyone tried disassembling the supplied multiboot image to figure out how to access the GW? It seems the Game Wallet has a lot of potential, if a suitable multiboot image could be created. Here are some examples:
- Make it work with other brands of flash cartridge.
- Since the GBA hardware can at least read data from the CF/SM card,
applications like movie or MP3 players should be possible.
- If writing to the CF/SM card is possible, you could backup saves from
your carts to CF/SM card, write photos taken with a camera accessory,
and generally use it as a portable storage device.

If only the manufacturer would release programmer/interface specs to make reverse-engineering unnecessary...

Now a question: does the Game Wallet connect only to the link port? If so, are ready-made link port extension cables available, to allow the GW to be placed away from the GBA?


M.

#20623 - tepples - Thu May 13, 2004 9:45 pm

The Game Wallet connects only to the link port. And here's how to build an extension cable out of solder and the parts in a standard GBA multiplayer link cable.

I've been looking for a disassembly of b@@t.gb@.mb since the Game Wallet came out.
_________________
-- Where is he?
-- Who?
-- You know, the human.
-- I think he moved to Tilwick.

#20628 - Helllo - Thu May 13, 2004 10:54 pm

tepples wrote:
The Game Wallet connects only to the link port. And here's how to build an extension cable out of solder and the parts in a standard GBA multiplayer link cable.

I've been looking for a disassembly of b@@t.gb@.mb since the Game Wallet came out.


Thanks for the link. As you probably know, there's a C-language include file at http://www.flash2advance.com/f2acfos.htm which would allow someone to write e.g. a picture viewer or MP3 player application. But of course direct access would be much more versatile. Nevertheless, assuming swapping CF cards with the power on is allowable/supported, the __absread function could allow files from e.g. FAT32 or other filesystems to be read.

The routine names in the include file could provide a starting-point for someone to reverse engineer the b@@t_gb@.mb file.

Re the disassembly... I would love to do that myself, but the best/most suitable disassembler (IDA Pro) is only sold to companies, not individuals. Sigh.

As an aside... sometimes a product's hardware capabilities are greater than that supported by the software. For example, take the MP-Xchanger. That product has slots for PlayStation & N64 memory cards, and GB (not GBA) cartridges. The supplied (PC) software allows reading and writing game saves from GB carts, but not game ROM data. However, the firmware in the unit allows reading game data, and writing to a variety of GB flash carts. (The MP-Xchanger uses a 6502 microcontroller, I have disassembled its firmware.)

M.

#20639 - tepples - Fri May 14, 2004 7:09 am

Helllo wrote:
Re the disassembly... I would love to do that myself, but the best/most suitable disassembler (IDA Pro)

You don't need IDA Pro to disassemble a program. You just need to put VisualBoyAdvance in a mode such that it marks addresses as code (last read was a fetch) or data (last read was an ldr). VBA may already have this mode in its GDB interface; if not, VBA is free software, so you're free to make and distribute a tracing patch like the one for Snes9x.
_________________
-- Where is he?
-- Who?
-- You know, the human.
-- I think he moved to Tilwick.

#20649 - torne - Fri May 14, 2004 9:03 am

IDA is sold to individuals too. The $400/$800 price tag is for *one* licence, not for a whole company. If a company wants more than one person to be able to use it at a time, they need to buy that several times over. =)

#20652 - Helllo - Fri May 14, 2004 10:39 am

torne wrote:
IDA is sold to individuals too. The $400/$800 price tag is for *one* licence, not for a whole company. If a company wants more than one person to be able to use it at a time, they need to buy that several times over. =)


Last time I asked (a year or so ago), Data Rescue were only willing to sell to companies, not individuals.


M.

#20666 - FluBBa - Fri May 14, 2004 3:41 pm

This might be usefull when emulating the PC-Engine CD-ROM, to put the complete CD om a Compact Flash, does anybody know if the gamewallet supports cards up to 1GByte?
_________________
I probably suck, my not is a programmer.

#20680 - ampz - Fri May 14, 2004 8:03 pm

The Compact Flash interface is size independent, so there is no hardware limitation until 136GB. There can however exist software (driver) limitations.
The most common limitation to my knowledge is that compact flash devices larger than 4GB cannot use FAT16. Larger than 4GB compact flash devices must use FAT32. Not all device's software support FAT32.