Linked by Thom Holwerda on Tue 22nd May 2007 00:15 UTC
IBM IBM finally took the wraps off its much anticipated Power6 microprocessor, which company executives said will double the clock speed of its current Power5 chip, without stretching the power envelope. The Power6 processor, unveiled at an event on May 21 in London, is a dual-core chip with a top clock speed of 4.7GHz, double the 2.3GHz of the Power5+ processors. The new chip also includes 8MB of L2 cache - four times as large as the current Power5 offering - and an internal bandwidth of 300GB per second. Ars' John 'Hannibal' Stokes obviously also has his say.
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RE[2]: Virtual Windows PPC
by Ravyne on Tue 22nd May 2007 18:20 UTC in reply to "RE: Virtual Windows PPC"
Ravyne
Member since:
2006-01-08

No, NO, NO!

The PowerPC cores in the 360's Xenon, the PS3's Cell, and the Wii's Broadway processor have *NOTHING* to do with Power4 or PPC970. The single resemblence the Xenon/Cell cores share with the 970 is that a subset of their complete instruction set is the 64bit PPC instruction set. That is where the similarity ends. The Wii's Broadway processor isn't even 64bit!


The PPC cores in the Xenon are functionaly identical to the PPC core in the Cell. The only differences are in the cache-control mechanism and in the communication mechanism -- The cell uses their "XO" communication fabric for off-chip communication and a ring topology to communicate with the SPE vector units, while the 360 uses Hypertransport (or something similar).

These cores are *not* derived from any commercially available PPC product line both Server or Desktop. These chips come from an experimental architecture IBM developed to push the limits of PPC architecture on a small, low-power die. While the PPC970 and similar power designs have out-of-order execution, these embedded PPC cores do not. These cores also impliment their duel-threaded execution in a novel way; In addition to a standard alternating scheduler, when one thread stalls (say on a memory accress) the other thread will execute.

The Wii's Broadway processor is based on the gamecube's Gekko processor, which in turn is based on the G3 PowerPC processor that was found in the early iMacs. Nintendo had IBM add some SIMD instructions for the Cube which overlap the FPU execution unit -- basically they added instructions to process a pair of 32bit floats using the silicon from the 64bit FPU. The Broadway processor's re-spun silicon simply runs faster, adds aggressive power-saving features and more fine-grained cache control, uses a smaller process, and likely has some minor silicon tweaks. IBM offers the exact same PPC core for the embedded market as a cheap, powerful, extremely low-power embedded CPU.

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