CPU/Graphics/Memory

Specifications of X-Box and PlayStation 2
	X-Box	PlayStation 2
CPU	600 MHz Intel	300 MHz MIPS
Graphics Processor	300 MHz custom-designed X-Chip, developed by Microsoft and nVidia	150 MHz Sony GS
Total Memory	64 MB	38 MB
Memory Bandwidth	6.4 GB/sec	3.2 GB/sec

Intel Inside

A 600MHz Intel Pentium III will be powering the Microsoft X-Box, a mild surprise. The conventional wisdom right up until the last minute was that AMD's Athlon would be MS's processor of choice for the X-Box. It's not known why MS switched over to Intel right at the last moment. It's possible that Microsoft didn't want to risk the kind of supply shortages that plagued AMD in the not so distant past. Bear in mind that Sony Playstation 2 sold nearly 1 million units in its first weekend alone, in Japan only! If X-Box is to take on the PS2, then it will have to sell at least as quickly as the PSX2. Volume deliveries of CPUs from a proven supplier will be a key issue here. Another theory

NVIDIA

It's interesting that NVIDIA, like Intel, was chosen at the last moment to power the X-Box. NVIDIA's primary competitor for the X-Box contract was upstart Gigapixel, a relatively new graphics company centered around tiling technology - a method of rendering that breaks up a scene into a number of smaller "tiles" and draws each tile up individually. It sounds promising, but again, it looks like Microsoft has taken the safe route, opting for the more proven of the two rival companies. Though it's being called "X-Chip," conventional wisdom (and Reuters) states that the chip will be the NV25 - a full 3 generations down the road from where NVIDIA stands today.

Update 3/13 8:00AM - NVIDIA denied yesterday that it was the NV25 powering the X-Box.

Share and share alike

With 64 MB of 200MHz double data rate (DDR) memory, X-Box will sport nearly twice as much RAM as the Playstation 2. Where Playstation 2 only allocates 4MB to video, X-Box's memory will be a unified system - shared by both the CPU and the graphics processor. This means that X-Box developers will have a lot more room to shove huge, detailed textures into games, without having to worry about leaving enough for the frame buffer. It's also worth noting that the unified memory architecture eliminates the need for a front side bus as we know it in PCs. This gives X-Box a massive bandwidth advantage over competing consoles. X-Box will have twice the memory bandwidth of a PSX 2.

In terms of bandwidth, the way in which the CPU and GPU share the same memory bank means that a single instruction, changing the store pointer, is enough to effectively transfer data from one processor to the other. The refresh rate of the memory is thus its effective bandwidth.