IBM has published official documentation of the Cell architecture. The documents are general specifications and do not describe the specific architecture of the PS3. What is interesting about it is that although it's a modern architecture, it has kind of a "retro" feel to it because it requires the programmers to possess more knowledge about the hardware architecture than we are used to. This is by design; the architecture is made simple so it can be made fast. As an example, it's up to the programmer to handle main memory transfers through DMA instead of using a cache (which takes precious space and power on the chip). Such "close to the metal" things bring back memories of programming the blitter on the Amiga...
As a side note, IBM's convention of numbering the bits starting with the most significant confuses the hell out of me. I.e. bit 127 of a 128-bit quantity is the rightmost bit, not the leftmost one.
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