A shift to Serial.

Discussion in 'Macintosh Computers' started by manitoubalck, Sep 25, 2003.

  1. macrumors 6502a


    Jul 17, 2003
    Adelaide, Australia
    We are now seeing Serial ATA replacing the old IDE/Parallel ATA and the dawn of Serial PCI Express for graphics cards to replace the Parallel AGP standard. Serial Attached SCSI (SAS) is in the works and is looking to be released within the next 2-3 years, with transfer rates as high as 600MB/s, marketed at high-end servers etc.

    USB 2.0, Firewire, Ethernet, V-Link, MuTIOL, HyperTransport®, RapidIO are all serial-based, so it is safe to say that the computing industry is moving away from Parallel data transfer methods.
    Why then are we still using DDR memory (current max clock on single channel 533MHz) when a Serial alternative has been around for 4 or so years? RDRAM or RAMBUS, was initially developed for use with the P4 and Xenon processors. It has single channel clock frequencies of 1600MHz, more than double that of the current fastest DDRRAM modules.

    RAM makes computers work faster, and the faster the RAM and the more you have the more effectively it can use the Chip’s FSB, hence the faster the computer can operate. Why not then have 8GB of RDRAM operating @ 1600MHz, rather than 4GB per channel operating @ 800MHz. I know RDRAM has suffered at the hands of a lack of consumer support due to it’s high cost, but with widespread adoption as has occurred with DDR there’s no reason that this superior Serial product should fall by the wayside. Even the Specs of DDRII from JEDEC don’t live up to those of RAMBUS.

    The Shift is to Serial, so why should RAM be left behind when it is so critical to system performance.

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  2. macrumors 601


    Feb 17, 2002
    So long, and thanks for all the fish!
    BETA and VHS

    MAC and PC


    RDRAM and DDR

    the first option is a bit more expensive (even though the quality is much greater) and so the general populous chooses the second. 'Tis the way of things.
  3. macrumors 65816


    Sep 10, 2003
    Most of the articles I've read show that DDR SDRAM gives you the same or greater performance versus RDRAM. Since RDRAM is much more expensive, why use it?

    Intel learned this lesson, hence the reason they use DDR on their newer boards. Plus, since hard drives and PCI busses seem to be the bottleneck now, increasing RAM speed won't help that much. Now that PCI-X is external now, it's time that they modify on-board components to use these technologies.

    Does anyone know of any documentation that states that onboard NIC's, audio, and ports on the faster G5's are actually on the PCI-X bus? Or are they going through a PCI bus and across a PCI-to-PCI-X bridge?
  4. Moderator emeritus

    Jun 25, 2002
    Gone but not forgotten.
    You might want to check the technical notes at http://www.apple.com/developer for the G5.
  5. macrumors 68020

    Jan 7, 2003
    Washington, DC
    Re: A shift to Serial.

    You might also look at the DRAM industry's regard for Rambus. Most of them aren't too pleased with Rambus's participation in JEDEC, the industry standard-setting organization. Or its subsequent efforts to strong-arm them on license agreements.
  6. macrumors member

    Jun 4, 2003
    Unlike most of the other standards you mentioned, where the serial challenger replaced a wider-but-slower system, RD-RAM's latency and lower width mean that it's not easy for it to even compete with comparably priced DDR solutions. Then you consider that Rambus is not loved, and you have an answer. It's one thing for Apple to use a technology reserved for more expensive machines (SCSI), another for them to use a technology that has totally exited the mainstream... for a reason.
  7. iPC
    macrumors 6502


    Jul 22, 2003
    East Windsor, CT

    Among other things. Not to mention that the price increase was not comensurate with performance increase.

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