[geeks] The new IPC/LX, from Dell?
alaric at metrocast.net
Fri Nov 20 10:44:10 CST 2009
Lionel Peterson wrote:
> As I recall, IDE was all about cheap drives, and reducing the silicon
> on the actual drive is how they did it.
> I *suspect* SCSI interfaces control the drives at a higher level,
> while IDE interfaces deal with the drive at a lower level. When I say
> interfaces I mean the 40 (IDE) or 50-68-80(SCSI) wires between the
> controller and the drive.
I recall that when IDE first came out, the drives actually seemed to be
smarter in some ways compared to other technologies on the market at the
time, and it seemed the interface talked to the drive at a *higher*
level. Setting up an ST506 drive, you had to know the exact physical
CHS geometry. You could hook up a SCSI disk, and say "What's your
geometry," and it'd say "I have X heads, Y cylinders, and Z sectors per
track." When you hooked up an IDE drive, the system would ask for its
geometry, and the drive would basically say something like "Tell me what
you'd LIKE my geometry to be, and I'll pretend."
Of course, these days everything auto-negotiates geometry, and just
about everything uses LBA48 addressing instead of CHS anyway.
Phil Stracchino, CDK#2 DoD#299792458 ICBM: 43.5607, -71.355
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