On 10 Feb 98 at 8:49, [log in to unmask] wrote:

>         -If you combine an HD and a slow CD on the same IDE cable,
> on most chipsets HD performance will be degraded (I think TX is
> an exception).

  Even 20+x CD-ROM drives are "slow" by hard drive standards.  There
apparently was a period when, as a result, most ATAPI CD-ROM drives
supported only PIO mode 1; most hard drives these days probably can
do mode 3 or 4, with some older ones limited to mode 2.  [Each mode
offers a top bandwidth about twice its predecessor.]
  As I understand it, each EIDE channel is limited to PIO modes
supported by both devices.  So if your CD-ROM drive only supports PIO
mode 1, guess what your hard drive is limited to...

  I have an impression that many CD-ROM drive manufacturers may have
corrected this, but I haven't seen that documented.

  This is the first suggestion I have found, anywhere, that a chipset
might be able to fix this.  It seems to me that that violates the
EIDE standard and so may introduce other incompatibilities.  Hmmm,
maybe that's why the TX chipset doesn't like some Seagate hard drives?

David G


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