lilbroex said:
Oh, I miread that. I thought you said PPEs pural, not possesive. Should have been Cell's PPE. Though that is still kind of strange to me. The cell was completed yet when the production model Xenon was originally released. |
Well, you read Millennium correctly. I'm saying the distinction between a PowerPC Core and a PowerPC Engine is minimal at best, especially when you look at later developments in the Power line of processors. What IBM engineered in the PPE was used in the Xenon, but what was engineered in the Xenon was used in the Power5+ line and future Power cpus.
The SPUs are what distinguished a Cell processor from your standard everyday Power5 cpu, not necessarily the PPE (PowerPC core).
People want to make a big deal out of the relationship between the Xenon and Cell, but there isn't a big deal to be made. It's a Power5 PowerPC core with some performance enhancements and management for the SPUs. Each of the Xenon's three cores are roughly the same as the PPE but without the SPU management enhancements. With six threads, the Xbox can run the game in one, and then the game can split itself off into 4 or 5 parts to process sections of code, much like the Cell can. The difference is that the Cell can do it in parallel to other operations, the Xenon does it symmetrically. So they can have an SPU do work, return the finished work, and move on to do another task. Where as on the Xenon processor, the game may be limited to waiting for a particular task to complete before it can move on.
That is were the difficulty in programming the Cell comes in. Micromanaging the code so that the SPUs are working, rather than waiting around for other tasks (SPUs) to finish. It is a difficult art to master. Kind of like conduction an orchestra were each of the musicians are playing a different piece of music, yet when it all comes together what you hear is one harmonious piece of music.
Sorry if I rambled.
