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Understanding 64-bit PowerPC architecture

Posted by CmdrTaco on from the expand-your-brain-pan-man dept.

An anonymous reader writes "Each of the leading microprocessor manufacturers has announced the availability of one or more 64-bit desktop processors, but differences exist in architectural design, fabrication, support, and intended use of each processor. This article looks at the critical issues in a few of IBM's 64-bit POWER designs, covering 32-bit compatibility, power management, processor bus design, and the manufacturing process."

8 of 116 comments (clear)

  1. Power != PowerPC by Computerguy5 · · Score: 3, Informative

    Power != PowerPC That is all.

    1. Re:Power != PowerPC by Arker · · Score: 4, Informative

      Power != PowerPC That is all.

      Hmm not exactly. Power > PowerPC. PPC is a subset of Power, a point which TFA does mention, and explain a bit.

      The PowerPC architecture that was born of this partnership is -- and always was -- a 64-bit architecture derived from the IBM POWER architecture.[...]
      Note that the performance of the PowerPC 970 family actually exceeds that of its award-winning parent, the high-end IBM POWER4 processor, in many areas. This is due to the fact that the circuit and process technology used for the POWER4 processor was designed to achieve levels of reliability necessary for the continuous availability server market -- levels that can be relaxed for the desktop and small-scale server market -- at the expense of transistor switching speed. Thus, the fabrication technology used for the PowerPC 970 was designed to eke out higher performance by trading away reliability; for these markets, the trade-off between reliability and performance is different.

      And yes, folks, it is a dupe. And a very recent one too. At least this time they got it in two different sections, first Apple, then Hardware. I'd have to say that Hardware is a better place for it, it's definately NOT just Apple that uses these chips.

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    2. Re:Power != PowerPC by dgatwood · · Score: 3, Informative
      At a user-mode instruction level, the POWER3 and POWER4 CPUs implement the PowerPC ISA. At the supervisor level, this isn't true, and for the POWER and POWER2, it wasn't true at the user level, either. (POWER and POWER2 had additional registers, for one thing.)

      Technically, the POWER series implement an ISA that is user-space-instruction-compatible with PowerPC. Subtle difference, I know, but....

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  2. Re:Super duper by jon787 · · Score: 3, Informative

    Yeah but that was on april fools' day and doesn't count. They were doing that on purpose.

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  3. Grammar Nazi! by Anonymous Coward · · Score: 3, Informative

    their means belonging to them.
    they're means "they are"
    there means not here.

  4. The explination of the difference by TyrranzzX · · Score: 3, Informative

    First, I'm talking a risc/cisc architecture like the x86.

    When you're talking about 64 addressing lines, your talking about addressing a fscksum of memory and devices. But, in addition, those lines allow for other possibilities: for example, sending 2 or 3 write commands with attached data and 2 32 bit addresses on the 64 bit bus simultaniously with an extra address decoder either on the chip or on the memory controller, or to some other device. Although, I don't know weither or not they've thrown that in as of yet. 64 bit numbers don't occur that often, afaik, but I'm not a coder so :P.

    The data bus advantage, however, is bigger. The x86 architecture has a command decoder, whereas you can send several commands in a single clock. With 32 more bytes, you get twice as many commands in a clock. Additionally, you can address more commands (but seriously, the first x86 had 38 commands, and that has increased by 10x in the past few years).

    Aside from that, you're throwing on more features into the processor. But, that's been here in the past 20 years of processor developement anyway. The article tends to be unclear on this. You're essentially expanding the bus to feed more buffers/pipelines.

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  5. Re:Ehh? by mrdisco99 · · Score: 2, Informative

    Yes.

    However, with this iteration, IBM took one of the cores from the dual-core POWER4 chip, repackaged it as the PPC970, and sold it to Apple as the G5. So PowerPC and POWER have re-merged... sort of. Freescale is still developing their own PowerPC chips which do not fall under the POWER umbrella.

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  6. Re:wow! by Anonymous Coward · · Score: 1, Informative
    He went off to write about dogs. No, seriously.

    http://www.workingdogweb.com/Katz.htm