KarbosGuide.com. Module 4b4.

Harddisks developments - continued

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    Speed generates heat

    Some years ago there was a problem with noise. I had to give up a Quantum SCSI-based disk, which turned at 7200 RPM with the sound of a dentist's drill. It was intolerable to be in the same room!

    The best SCSI disks available rotate at 10,000 and 14,000 RPM. They are expensive but ultimately they provide the highest transfer capacity.

    Check this company for hard disk cooling gizmos. Here is one:

    The controller principles

    Further down this page is a review of the interfaces which are used for hard disks. But, first look at this brief summary:

    Controller Description
    MFM, RLL
    and ESDI
    Older standards for hard disk interface
    IDE Simple, primitive interface. Data are delivered on the ISA bus, resulting in low transfer speed. Disks < 528 MB. Is not used on new PCs.
    EIDE Improvement of IDE. Data are delivered on the PCI bus with Bus Master control, which results in high transfer speed. Large disks (currently up to 40 GB). Room for four units, which are typically connected directly to the system board. Inexpensive and effective disks. Ultra DMA is the best interface among the EIDE varieties.
    SCSI High end controller system, where the units are connected to a special (expensive) controller. The hard disks are generally of highest quality, fast and with a long life span. An ordinary SCSI controller can run 7 hard disks each of 45 GB - or more. The latest IBM Ultrastar 72ZX holds 72 GB and a cache of 16 MB.

    All together we have several technologies which all can be optimized for making better hard disks:

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    Learn more

    Also see Module 4c1 about optical media (CDROM and DVD).

    Also read about EIDE and UDMA

    And about the most advanced and elegant controller principle of all: SCSI.

    Read module 7a about monitors, and 7b on graphics card.

    Read module 7c about sound cards, and 7d on digital sound and music.

    HD Tach - a fine program to test harddisks.

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