Comment Re:Cell (Score 1) 338
I'm speaking more to characteristics of the end result, rather than lineage. At the broad level, both the original Atom and the PPU in the Xbox360 and Cell are dual-issue, in-order processors that use thread-level-parallelism (hyperthreading) to keep the CPUs execution units fed. Neither the PPU nor Atom(including the original Pentium) supported instruction re-ordering, register renaming, or speculative execution -- the only instruction level parallelism any of these designs can extract is that two adjacent instructions can be issued if there's no dependency between them. These design choices are very different than the fast single-core (what I call a 'fat' core) that are typical of mainstream, high-performance CPUs of the day, through today, like the Pentium 4, Athlon, Power4, or Intel's current i-series.
However, one thing I had forgotten about the PPU in the Xbox360 is that it wasn't just that the SIMD Altivec units were given a larger register file and some tweaked instructions -- There's actually two full, independent SIMDs per core, one for each thread. The one in the Cell only had one SIMD and its register file wasn't extended, AFAIK.
However, one thing I had forgotten about the PPU in the Xbox360 is that it wasn't just that the SIMD Altivec units were given a larger register file and some tweaked instructions -- There's actually two full, independent SIMDs per core, one for each thread. The one in the Cell only had one SIMD and its register file wasn't extended, AFAIK.