[EMAIL PROTECTED] wrote in a message to Mike Bilow:
p> I have a beautiful Seagate Barracuda scsi drive just begging
p> to be dropped in a machine and used for Linux/ham radio. Its
p> an ST 12550 ND and its in the current Seagate catalog and
p> literature, which I have downloaded. Note the ND (narrow
p> differential) suffix ..... But how do I use it ?? Who does
p> controller cards for these beasts ??
* * *
p> I the took the phone bill by the throat and phoned the
p> Seagate scsi helpdesk in California. The best the man there
p> could do was choke up, and then deny that a "Seagate
p> Barracuda ST 12550-ND" drive was actually a Seagate product.
Seagate, as do many drive manufacturers, distinguish between their retail
products and their OEM products. It is possible that the ST12550ND was only
made on request for some particular OEM. Seagate drives are modular
constructions, so it would be possible for them to take a standard head-disk
assembly used on the ST12550 and make up the ND version. Seagate may well
choose to regard such an OEM special order as not their product.
There are differential controllers, but it is also quite common to use
differential to single-ended converters. These usually look like small boards
with a SCSI connector on each side. In fact, most drive manufacturers only
make single-ended drives, and they add a converter board if they need to make a
differential assembly. The only advantage of differential over single-ended is
that the noise immunity is greater, which allows a longer physical bus.
-- Mike
