Differential SCSI vs. SE ? - test-drb@ccmp.vtda.org

12 Feb 2003

Pat,

The CMD CQD-420/TM design uses a daughter card of which there
is a single-ended version and a differential version. The differential
version should actually be a little less expensive because most users
want the single-ended, and the cost of getting a single-ended daughter
card to replace the differential one is expensive. Therefore perhaps better
supply and lower demand for differential. I DON'T HAVE ANY OF THESE
ANYMORE. THEY WERE SOLD, to a buyer in the mid-west. But you can
find them searching Google. But even the differential ones still are more
than all but the most exceptional hobbyist would want to get in to.

Best Regards

At 06:52 PM 2/12/03 -0500, you wrote:
...
 On Wed, 12 Feb 2003, Fred N. van Kempen wrote:

  All,

 Now that I inherited a nice set of StorageWorks enclusures with
 an HSZ40C controller, I might as well use it, no?  I plan on
 connecting it to the primary file server of my "fun" network
 (also known as VAXlab, aka pdp11.nl) so I'll have more (and safer)
 storage there.

 Only prob is.. the HSZ40C has a diff-scsi port, whereas the machines
 have SE.

 Is this easily converted with a cable, or will I be doing resistor-
 balancing and/or use a signal converter box? 
It can't be done with just passive components.. ie you will need either a
differential<->single-ended converter or a differential SCSI card.  If
you're using a machine that takes PCI cards, then a card will be cheaper,
but if you're using it with a VAX or PDP-11, etc, I'm doubtful you'll find
a differential-scsi interface, and will need to buy an interface box.

If you need/want a PCI wide/differential SCSI card, I have several Adaptec
AHA-3944AUWD's (with PC BIOS ROMs) that I would be willing to sell at a
'reasonable' price (probably $40 + shipping).

As far as 'converter boxes' go, I don't know what one would cost, because
I've never had to buy one.

Pat
--
Purdue Universtiy ITAP/RCS
Information Technology at Purdue
Research Computing and Storage
http://www-rcd.cc.purdue.edu 