The latest generation of this lovely processor is the G4, also known as the PowerPC 7400. At the time of writing, it's running at up to 500Mhz in PowerMacs. AltiVec has been renamed Velocity Engine by Apple, presumably for marketing reasons.

Cycle for cycle, PowerPCs are faster than chips based around Intel's x86 architecture, and AltiVec gives the G4 a significant boost in certain types of tasks. At the time of writing, x86 is nullifying that advantage through sheer brute force, running at up to about 1Ghz, but 800Mhz G4s are on the horizon.

The PowerPC has other advantages, however, including a smaller form factor, and more efficient power management. The fastest x86 chips are unsuitable for use in portable devices, as they generate too much heat, while Apple is able to put its fastest G3 chips into its Powerbooks, making them the fastest laptops you can buy. As yet, the G4 doesn't run cool enough to put into a laptop, but this is likely to change in the near future.

The PowerPC line has a roadmap which stretches into the future for at least another couple of generations (see Motorola's site), while Intel are planning to pretty much totally replace x86 with something else entirely.

The PowerPC is jointly developed by Apple, IBM and Motorola. IBM contributed the multiprocessor design (POWER architecture as used to realize someof the first RS/6000), Motorola the I/O part (using the 88000) and Apple the computer design. The life of PowerPC is a very interesting story, which involves IBM trying to make Intel x86 compatible processor... in hardware, almost like the codemorphing technology Transmeta uses for their Crusoe.

The PowerPC is now mainly used by Apple to power their desktop and notebook computers. Even the Amiga had/has a PowerPC acclerator board, know as the BlizzardPPC. Motorola now manufactures embedded networkprocessors based on the PowerPC design, known as PowerQUICC. Nintendo uses a IBM variant, the Gekko, to power their GameCube.

A very well known computer powered by PowerPC processors, was the IBM Deep Blue project. It even beated Kasparov.

Update - the latest revision of this chip is the dual-core PowerPC 970FX, which is a dual-core version of the 64-bit PowerPC 970, AKA G5. This chip hasn't found its way into any Apple products as yet, but several of the newer IBM P-series workstations and servers are based on these chips. Available operating systems include Linux, AIX and most likely NetBSD. (Rest assured that if NetBSD doesn't yet run on the 970FX, it will soon!)

The stalwart PPC7400 has received a major speed boost, too, running at a maximum of 1.66 GHz. It forms the core of the iBook, Powerbook and Macintosh Mini lines, which are currently not based on 970s for reasons of cost or power dissipation.

64-bit chips of the PowerPC series, like the UltraSPARC and AMD64 series, can run unmodified 32-bit binaries with only a minor performance hit (and, paradoxically, a performance gain in some odd edge cases, because 64-bit values are larger and take longer to copy about in RAM). Currently, Mac OS X, the best-known OS for PPC, is 32-bit (but can run 64-bit applications). The next OS X release will have native 64-bit capability on PPC970 machines. Linux, NetBSD and AIX already can run in native 64-bit mode.

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