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Apple Dual G5 Desktop


Apple produces fantastic looking high-performance laptops, with innovative features. However, until recently its desktop range was hampered by inherent performance problems with the G4 processor family, produced by Motorola.

This caused multiple problems for Apple, and for its core clientele in the creative community. Effective processor speed began to look poor compared to high-end Windows graphics workstations. In addition, the upgrade to OS X was not that attractive to power users of Macintosh systems, due to the lack of key applications ported to the new operating system. This lead to the slightly insane situation of a home user with an iBook or iMac having a more modern machine and operating system than that of a graphic designer.

Now however, that situation has completely changed; Adobe Photoshop now runs natively and a completely new version of OS X (Panther) offers some important upgrades. Equally as important though, is an entirely new motherboard and chipset combination for the desktop: the G5.

Now, we are not talking a minor change here or some technological tweak. This is more than a new generation of PowerPC hardware; it is a completely new species of desktop architecture, which offers parity with the users of high end work stations.

The first thing you notice about the new motherboard is that it allows the installation of up to 8GB of RAM. The maximum addressable memory on any PC style machine (barring an {AMD 64 platform of course) is 4GB. This doubling of maximum RAM is due to the replacement of the G4’s 32bit architecture with the 64bit architecture of the G5. Before now the only 64bit stuff you’d find on the desktop would be kit from Silicon Graphics or Sun, running UNIX. The execution core of the G5 chip is taken from the IBM processors used in its eBusiness servers, so the pedigree for speed and for future development is excellent.

This might seem to be an excessive provision, but ask any graphic designer and the term 'enough' isn't in their IT vocabulary; especially when it comes to memory.

Currently 8GB is the uppermost limit on RAM as, quite sensibly, Apple has left the G5 chip 64bit to 32bit scalable. Apple made a complete break with the past when it went over to the original PowerPC chipset, and doing so again would mean running legacy software through some form of emulation, and even with the G5’s impressive raw processing power, applications would probably crawl under that kind of environment.

However, having this potential memory capacity wouldn't make much difference in the real world without a databus architecture that could handle the load. In the case of the G5 this has been taken care of in fine style, with a 1GHz bus feeding each of the 2GHz processors. Earlier Macs had highly restrictive bus speeds, the last iteration of the G4 desktop had a bus speed of 167MHz. The phrase ‘vroom, vroom’, does rather spring to mind, and currently all G5 systems will have a bus speed 50% of the core processor speed. As IBM has already stated, it can ship 3.0GHz chips by the end of 2004, so the development curve looks pretty good. So fast is the data throughput that Level 3 cache has been left out of the system, being deemed unnecessary.

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