A PowerPC in your iPhone?

Apple has agreed to purchase PA Semi, the designer of a 64-bit, power-conservative, dual-core processor, Forbes reports. PA Semi's chip is based not on Intel x86 (like Macs) or ARM (like the iPhone) processor specifications, but rather on the PowerPC platform around which Apple no longer bases new systems but still actively supports with Mac OS X. Unlikely to divert attention from the Intel processor for full-fledged Macs, Apple may be planning to utilize PA Semi's current processor line, dubbed PWRficient, or a still-in-development chip from the small fabless designer in the iPhone or an unannounced product line.

PA Semi's PWRficient PA6T-1682 is a monster when compared with the iPhone's current 620 MHz ARM CPU. It's dual-core, with each core running at 2GHz, and sports two DDR2 memory controllers, 2MB of L2 cache, and a robust I/O subsystem. It's also significantly more power-hungry than the ARM chip, however. The PA6T-1682 draws 5-25 watts depending on application, and can drop down to 1 watt in power-saving model. The iPhone's ARM processor draws 0.45 milliwatts per MHz. The current iPhone's processor is clocked at somewhere around 400 MHz, meaning it draws about 180 milliwatts, or .18 watt. As such, the PA6T-1682, in its available form, won't meet a typical iPhone's low power consumption requirements. Intel's Core 2 Duo processor (used in various Macs), for comparison, draws a maximum of 65 watts.

Intel's forthcoming Atom processor seemingly makes more sense as the centerpiece of a future iPhone than PA6T-1682. The Atom's power consumption ranges from subwatt to 2.5 watts for mobile devices.

Apple is, however, buying not only the extant PWRficient processor design but also ARM expertise. Dan Dobberpuhl, CEO of P.A. Semi, worked on the original Strong-ARM processor processor -- a successor to which is currently used in the iPhone -- at Digital Equipment Corporation.

Dobberpuhl revealed in mid-2006 that his firm was working on a variety of processor cores at "different power points." As such, P.A. Semi could have chips in the pipeline that would suit the iPhone nicely.

Since the iPhone runs a mobile version of OS X, which uses the same basic foundation as the PowerPC and Intel compatible Mac OS X, reworking the iPhone's basic software to run on a PowerPC platform such as P.A. Semi's is theoretically feasible.

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