SUMMARY: Sun scsi differential discs on Sun differential controller

From: Leonardo C. Topa (
Date: Sat Jul 24 1993 - 04:24:17 CDT

I recently asked:

From: (Leonardo C. Topa)
Subject: Sun scsi differential discs on Sun differential controller
Date: Tue, 13 Jul 93 13:44:26 EDT

I have three scsi differential discs purchased from Sun (to nobody's
surprise, their label says Seagate ST42400ND though) which I am trying
to attach to a Sun DSBE/S s-bus card. The drives are physically
mounted in a rack mountable enclosure in which up to 4 drives can be

My problem is that the controller has a mini-DB-68 connector, whereas
the enclosure for the discs has the usual mini-DB-50 connectors. The
discs actually come with a 50 pin connector as well, so somehow I
believe 50 pins is all I need. (68 pins would be necessary for wide
scsi only, I surmise...)

Therefore the question is: what is the pin by pin description of the
scsi connector on these discs? I have the pin-out for the scsi
controller connector, so if I know what pins are actually necessary, I
can have a cable made for this.

Related question: the controller came with a 68-pin scsi terminator
which says it's expressly designed for differential busses. So, is Sun
using 68-wire scsi cables as well? In other words, if I had a Sun
expansion pedestal, would I need 68-wire cables all the way and
somehow 18 wires are dropped inside the pedestal?

As I imagined, the answer is that 68 pins are needed for wide-SCSI.
The discs that Sun sold me are differential-, but not wide-SCSI, so 50
pins are enough. Sun sells 68-pin cables (from 1 metre to 12 metres in
length) and inside its pedestal 18 wires are dropped. After some
searching for the right connectors, I have my discs up and running.

Thanks to: (Martin Kelly) (Sven Ole Skrivervik)
csfb1!phantom! (David Smith) "Joseph Kwan"
Mike Raffety <> (Daniel Strick)
Christian Lawrence <> (Mark Davis) --- prize for best answer!

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