Microsoft details new Xbox 360 SoC

Posted by Aharon Etengoff

Microsoft has published a virtual tear down of its new system-on-a-chip (SoC) that powers the Xbox 360 Slim.

The SoC - which previously identified by Anand Lal Shimpi of AnandTech - is produced on the IBM/GlobalFoundries 45nm process.

According to Ars Technia's Jon Stokes, the processor is the first mass-market, desktop-class chip to combine a CPU, GPU, memory and I/O logic onto a single piece of silicon.

"Consolidation lower(s) the cost of making the console by reducing the number of different chips needed for the system, shrinking the motherboard and reducing the number of expensive fans and heatsinks," explained Stokes.

"The SoC also makes the new Xbox design more power efficient...but the real motivation behind boosting the console's efficiency is to reduce the size and cost of the power supply unit and to realize the savings on [the] cooling apparatus."

Stokes noted that Microsoft engineers apparently did "a lot" of the layout themselves, which predictably presented more than "a few" interesting challenges.

"[For example], it would have been easier and more natural to just connect the CPU and GPU with a high-bandwidth, low-latency internal connection, but that would have made the new SoC faster in some respects than the older systems. 

"So they had to introduce this separate module onto the chip that could actually add latency between the CPU and GPU blocks and generally behave like an off-die FSB."

He added that the infamous RROD (Red Ring of Death) that had plagued earlier version of the popular console was "probably not" a factor in the new design.

"That problem has been solved for a while now, so the new SoC approach was really about making the console smaller, cheaper, cooler and quieter...[Indeed], the new 45nm SoC draws over 60 percent less power and reduces the total silicon area by over 50 percent."