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The Power Mac G5 is Apple's marketing name for models of the Power Macintosh which contain the IBM PowerPC G5 CPU. The professional-grade computer was the most powerful in Apple's lineup when it was introduced, widely hailed as the first 64-bit PC, and was touted by Apple as the fastest personal computer ever built. It was officially launched as part of Steve Jobs' keynote presentation in June 2003 at the Worldwide Developers Conference, and saw three revisions to the line before being retired in August 2006 to make way for its Intel replacement, the Mac Pro. The Power Mac G5 has an anodized aluminium chassis.[1] It was the final desktop manufactured by Apple to use a PowerPC CPU.
[edit] IntroductionThe Power Mac G5 was introduced with three models, sharing the same physical case, but differing in features and performance. The 1.6 GHz model shipped with 256 megabytes (MB) of RAM, an 80 GB hard drive, and could employ a maximum of 4 GB of RAM. The 1.8 and dual-processor 2.0 GHz models shipped with 512 MB of RAM, and could employ a maximum of 8 gigabytes (GB) of RAM. The dual-processor model also included an ATI Radeon 9600 graphics card. Steve Jobs stated during his keynote presentation that the Power Mac G5 would reach 3 GHz "within 12 months." This would never come to pass; after three years, the G5 only reached 2.7 GHz (or dual-core at 2.5 GHz) before being replaced by the Intel Xeon-based Mac Pro, which included processors with speeds of up to 3 GHz, and after three years is presently at 3.2 GHz. During the presentation Apple also showed Virginia Tech's Mac OS X computer cluster supercomputer (a.k.a. supercluster) known as System X, consisting of 1100 Power Mac G5s operating as processing nodes. The supercomputer managed to become one of the top 5 supercomputers that year. The computer was soon dismantled and replaced with a new cluster made of an equal number of Xserve G5 rack-mounted servers, which also use the G5 chip running at 2.3 GHz. [edit] PowerPC G5 and the IBM partnership  The PowerPC G5 (called the PowerPC 970 by its manufacturer, IBM) is based upon IBM's dual-core POWER4 microprocessor. At the introduction of the Power Mac G5, Apple announced a partnership with IBM in which IBM would continue to produce PowerPC variants of their POWER processors. According to IBM's Dr. John E. Kelly, "The goal of this partnership is for Apple and IBM to come together so that Apple customers get the best of both worlds, the tremendous creativity from Apple Computers and the tremendous technology from the IBM corporation. IBM invested over $3 billion US dollars in a new lab to produce these large, 300 mm wafers." (This lab is a completely automated facility located in East Fishkill, New York, and figures heavily in IBM's microelectronics strategy above and beyond the partnership with Apple). The original PowerPC 970 has 50 million transistors and is manufactured using IBM CMOS 9S at 130 nm fabrication process. CMOS 9S is the combination of SOI, Low-k dielectric insulation, and Copper interconnect technology, which were invented at IBM research in the mid-1990s. Subsequent revisions of the "G5" processor have included IBM's PowerPC 970FX (same basic design on a 90 nm process), and the PowerPC 970MP (essentially two 970FX cores on one die). Apple refers to the dual-core PowerPC 970MP processors as either the "G5 Dual" (for single-socket, dual-core configurations), or Power Mac G5 Quad|G5 Quad (for dual-socket, four-core configurations). The Power Mac G5 line in 2006 consisted of three, dual-core PowerPC G5 configurations, operating at 2.0, 2.3, and a dual-processor 2.5 GHz configuration (the dual contains four cores in total, two per processor). A 2.7 GHz single-core model was also released. It contains PCI-X slots, where the newer models use PCI Express. The dual-core G5 configuration can communicate through its FSB at half its internal clock speed. Each processor in the Power Mac G5 has two unidirectional 32-bit pathways: one leading to the processor and the other from the processor. These result in a total bandwidth of up to 20 GB/s. The processor at the heart of the Power Mac G5 has a "superscalar, superpipelined" execution core that can handle up to 216 in-flight instructions, and uses a 128-bit, 162-instruction SIMD unit (AltiVec). In addition, due to the 64-bit processor (and 42-bit MMU) the Power Mac G5 has a RAM capacity greater than the 4 GB addressable memory limit of traditional 32-bit processors. Currently, the Power Mac G5 can hold 16 GB of RAM using eight memory slots with 2 GB per stick. All modern 32-bit x86 processors since the Pentium Pro have the Physical Address Extension (PAE) feature, which permits them to use a 36-bit physical memory address to address a maximum of 236 bytes (64 gigabytes) of physical memory, while the PowerPC 970 processor is capable of addressing 242 bytes (4 terabytes) of physical memory and 264 bytes (16 exabytes) of virtual memory. The memory in this final revision of the Power Mac G5 is Dual-Channel DDR2 PC4200, with support for ECC memory. [edit] Product revision history(Note: DP designates a dual-processor machine, and SP designates a single-processor machine)
[edit] A partial list of official firmware updates
[edit] Electronic audio interference problemsEarly versions of dual processor G5 computers have noise problems. The first one is ground loop-based interference,[5] which sometimes causes noise leaks into the analog audio outputs. This bug was fixed in Rev. B G5. The second noise problem came from the 'chirping' sound, which can be triggered by fluctuations in power draw. For example, showing and hiding the Dock makes a brief chirp. Many had blamed the power supply used in the G5 as the cause, but this theory has never been confirmed. A very effective work-around is to disable the CPUs' "nap" feature using Apple's CHUD Tools, but this was not recommended by Apple. This noise problem was not fixed until the dual core generation of G5s was produced. The power draw fluctuation was later attributed to the lack of power management features in the single-core processors.[6] Apple eventually posted the chirping bug information on its support site.[7] Although the noise problems did not prevent the affected computers from working, they were problematic for audio professional and enthusiasts alike, especially for the liquid-cooled models, which had been expressly designed as mechanically quiet for discerning listeners. [edit] P.A. Semi's G5 derivativeWhen P.A. Semi announced the preliminary pre-production plan of PWRficient processor,[8] there had been persistent rumors that Apple would prepare for its use it in its professional line of personal computers.[9] In 2006, The Register reported that P.A. Semi had formed a tight relationship with Apple, which would result in P.A. Semi promptly delivering processor chips for Apple's personal computer notebook line and possibly desktops.[10] Even in 2006, Apple did not have a laptop version of G5 processor. The processor that would run the personal computers was P.A. Semi's preliminarily proposed processor, PWRficient 1682M (PA6T-1682M). The version that would be sampled for pre-production at third quarter of 2006 was a 2 GHz, dual-core CPU with two DDR2 memory controllers, 2 MB of L2 cache, and support for 8 PCI Express lanes. The sampled chip also has lower heat intensity than Intel's Core Duo, which gives off 9–31 W under normal load. According to The Register article, P.A. Semi executives believed they were all but assured winning Apple's contract, and CEO Dan Dobberpuhl thought Apple's hints of moving to Intel were just a persuading tactic. At the time, the companies were working for PWRficient software. Dobberpuhl was purple with rage when he learned of the Intel deal. Ironically Apple purchased P.A. Semi on April 23, 2008. Despite the advantages of more compatible architecture, Apple moved to the Intel architecture officially for 'performance-per-watt' reasons. However, P.A. Semi would not be able to ship its low-power multicore product in volume until 2007, which, combined with P.A. Semi's status as a start-up company, seems to have been the final blow to the development of Power Mac computers. However, it was also speculated that Apple switched to Intel processor because Apple could no longer abide the constant delays in performance ramp up,[11] desired native Windows compatibility, or it was Apple's strategy to shift its business focus to iPod and its global ecosystem. [edit] Notes
[edit] External links
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