Path: utzoo!utgpu!utstat!jarvis.csri.toronto.edu!mailrus!cornell!uw-beaver!rice!sun-spots-request
From: aad@stepstone.com (Anthony A. Datri)
Newsgroups: comp.sys.sun
Subject: Re: Xy 753 cables
Message-ID: <2756@stpstn.UUCP>
Date: 2 Feb 89 23:56:32 GMT
References: <8901191545.AA07757@natinst.com>
Sender: usenet@rice.edu
Organization: The Stepstone Corporation, Sandy Hook, CT
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Approved: Sun-Spots@rice.edu
Original-Date: 25 Jan 89 22:37:45 GMT
X-Sun-Spots-Digest: Volume 7, Issue 134, message 2 of 5

brian@natinst.com (Brian H. Powell) writes:
>Near as I can tell from the disk drive docs, you can either hook up the
>A-cable as a daisy-chain configuration or a star configuration.  (And you
>have to terminate the end(s).)

The Sun documentation I have even has a picture of how to cable, and they
show a data cable going from the controller to each drive, and the command
cables daisychaining.  That command cable is something like a 60 pin berg
connector, and in my fairly limited experience I've never seen a
controller that had more than one command connector.  In short, daisy
chaining them seems to be the right thing to do.  How many total disks are
you running off that controller?  Four disks off of one controller aren't
going to give you quite the max aggregate throughput of four disks off of
four or even two controllers, but unless you're accessing the hell out of
every drive on that controller I wouldn't be that concerned about it.

>If we don't daisy-chain, any suggestions on how to make the cable?  Any
>tricks to it?

If you didn't daisy-chain, what would you do, make an octopus?  That'd be
pretty much the same electrically, I think.  The SMD drives I've seen have
dip switches to set the unit number, so the unit number would seem to be a
couple of those command signals.  Ah for the days when drives had unit
select plugs on the front...

>Also, does anybody know what you call those connectors that are on the
>Xy753?  I'm used to DB connectors with nice big pins.  I haven't ever seen
>those small tight pin jobs before, so I don't know what to ask for.

I've never seen a 753, but if they're like just about every other board
made in the last 15 years, it's what DEC calls a "Berg" connector.  Many
of the connectors on DEC stuff actually do say "Berg" on them, and most
people seem to call them that.  I once spoke to someone who got very
perturbed with me for calling them that.  He didn't have a very memorable
alternative.

-- 
Anthony A. Datri @SysAdmin(Stepstone Corporation) aad@stepstone.com stpstn!aad