xbox 1 (original) mod chip info

[lilshawn]

i have an xbox i'm planning to test a theory with. this idea consists of flashing a new bios to the xbox and this bios is of a 512k variety.

the xbox i'm planning to do this to has a 256k flash in it currently and it also has an Aladdin? (looks like a 16k) modchip installed with xecuter bios already. this modchip also has a 256k flash chip of it's own that is removable.


I know not a lot about chip mods (opting mainly for softmods)

But, does this modchip replace? inject? a replacement bios during bootup? is it possible to place a 512k chip in the Aladdin chip holder with my modded bios and have it load on boot?

[Slippyblade]

No clues.  But I'm subbed cause I'm super interested in how this works.

[SNAAKE]

I can't remember but I think there was a software that let you resize any bios.

[lilshawn]

well, let me tell you my plan...

see, I have this chihiro game that the board crapped out in this particular chihiro board is basically an xbox debug board with a custom bios in it. I have a dump of the xbox bios for the chihiro board on my computer.

the original chihiro board had a 512k bios and this xbox board i have has a 256k. (apparently this particular revision has either a 256 or 1mb flash size.

if i can get the xbox board booting with the chihiro bios I will be able to solder on the additional ram to the board and basically make this baord a "debug" board and get this thing going again.

as far as i can tell the only difference i can see being an issue is the mcpx-x3 chip (which the debug board has a mcpx-x2 chip).but as far as the info i can tell, this chip really only handles the audio. an earlier version shouldn't make much of a difference. it's worth a shot anywho.

this motherboard i have has this modchip on it. if it works the way i think it does, perhaps i can throw a 512k flash in there with the chihiro bios on it and have it boot. otherwise i'm looking at removing the bios flash and "upgrading" it from 256k to 512k

[Howard_Casto]

I've always wanted to do that.  Lots of cool stuff ran on chihiro. 

[obcd]

I know this is a rather old topic, but wanted to add my 5 cent.
The first xboxes (1.0) had a 1MB Flash Tsop chip. It might we worth trying to find one of those, as you can leave half of it with a normal xbox bios and the other half with the chihiro bios. This gives you the option to reflash the Chihiro Bios when needed.
The chihiro uses the LPC for it's connection with the other board. This might make it difficult to install a modchip. The earlier rev. of xbox mobo's have most (all?) pin's of the LPC connected. The more recent rev. have some pin's of that LPC unconnected.
The MCPX chip is also responsable for the execution of the Xcodes in the bios, and they are different between the MCPX2 and MCPX3. So, you will likely need to modify your chihiro bios to make it run on the MCPX3. I am playing with the same ideas. All above comes from research I did on the topic, but isn't confirmed or tested. The xbox mobo ramchips are still available on Ebay. Soldering some new ones is easier than soldering some you removed from another xbox board. I have no idea if the chihiro uses the contents of the eeprom, but they are different from an xbox eeprom. Good luch with your project.

[lilshawn]

ive seen some posts regarding playing chihro games on moded xboxes with some sucess...mainly because they have to patch the software to with with NO hardware.

being that I have all the original hardware in a cabinet and everything...stands to reason I should be able to simply mod the board with the bios and the extra RAM and be GTG.

as a side note, I have a half dozen xboxes here to work with. i did peel out a board with a 1mb flash ROM so I should be able to use that. I';ll just have to mod the power connection.

so step 2.... does anybody know an easy way to flash this into the xbox? I suppose i can build something.

[obcd]

have a look at Tsop flashing for the original xbox. If I remember well, you could split a 1M tsop in 2 512 MB areas. You had to connect an adress line to either Vcc or GND. You have to reconnect one link to the flash wr, and you can reprogram the flash in circuit with software.
If something goes wrong, you can switch to the other flash half and boot from there.