IBM, Sony and Toshiba have revealed further details of the Cell processor.

Properly called the Cell Broadband Engine Architecture (CBEA), any CBEA chip will have one or more 64-bit Power architecture-based Power Processor Elements (PPEs) and multiple SIMD Synergistic Processor Elements (SPEs). Each SPE is an independent processor running its own application programs.

A shared coherent memory, including main memory, and DMA commands provide communication between all Cell processing elements (see panel below).

The PlayStation Cell has one PPE and eight SPEs.

An eight way Cell processor

SPEs are “optimised for running compute-intensive applications, not for running an operating system”, said IBM. “The designation synergistic for this processor was chosen carefully, there is a mutual dependence between the PPE and the SPEs.”

The SPEs depend on the PPE to run the operating system and, in many cases said IBM, the top-level control thread of an application. The PPE depends on the SPEs to provide the bulk of application performance. SPEs are designed to be programmed in high-level languages.

“To an application programmer, the Cell Broadband Engine looks like a nine-way coherent multiprocessor,” said IBM.

www-128.ibm.com/developerworks/power/cell/