CPU datasheet?

Does anyone know if the datasheet for the XBox CPU is floating around? My understanding is that the CPU was somewhat unique to the XBox and damned if I can't find a pinout.

Mainly trying to find out how the CPU gets the frequency for the FSB. Probably time to dig out my copy of Bunny's book.

 

I was under the impression that it was a mobile PIII Coppermine with half th L2 cache

 

You could ask if trusty (the guy doing the 1.0 and 1.4 g boxes) from scenyx tells you a little about it as I suppose he needs to know how it works.

If you want I could provide pictures from my 1.4 gbox when I come home at like the beginning of the week.

 

I'm mainly trying to determine how the XBox determines what clock rate it should run at assuming it isn't hard wired in. So far it looks like the GPU helps determine the FSB and the multiplier is locked.

 

Im pretty sure all he does is grab the high end server cpu from the same family as the xbox (P3) and installs it.

 

Not quite that simple but ultimately yes. He either uses a Pentium III or a Pentium III-S; the former has 256kb of L2 the latter has 512kb of L2. In theory the extra L2 offers performance increases but virtually every CPU I've looked at in depth that has such variants usually has a marginal improvement that can't be justified by the market price when launched.

Regardless he pops off the CPU, drops in a BGA->ZIF Socket 370 where the new CPU is held. The heatsinks I've seen are custom made with the entire retaining bracket removed from the XBox. To my knowledge there is a bit of rewiring done for sure but I think it is mainly for voltage reasons.

The Friendtech XBox had a switch that could drop the 1.4ghz CPU down to 740mhz or so. IIRC it was able to do this by forcing the CPU to execute instructions every other cycle as opposed to feeding the CPU a different FSB speed. Ultimately I'd like to see if the XBox can be overclocked but it would seem it is just slightly beyond my technical expertise as well as resources (no rework station etc).