Path: utzoo!utgpu!watmath!clyde!bellcore!rutgers!rochester!pt.cs.cmu.edu!cadre!pitt!darth!liber
From: liber@darth.UUCP (Eric Liber)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Need info on Quantum hard drive
Message-ID: <416@darth.UUCP>
Date: 9 Dec 88 13:39:08 GMT
References: <392@deimos.cis.ksu.edu>
Organization: Darth Software, Allison Park, Pa.
Lines: 41

> Does anyone know anything about the Quantum Q540 hard drive?  Is this a
> standard ST506/412 interface drive?  If so, what XT or AT controller
> works best with it?
> 
> Thanks for the info.
> 
> ***/\/\****/\/\******/\/\****/\* Saiid Paryavi                      
> **/*/\*\**/*/\*\****/*/\*\**/*/* paryavi@ksuvax1.cis.ksu.edu       
> */*/**\*\/*/**\*\**/*/**\*\/*/** paryavi@ksuvax1.BITNET           
> *\/****\/\/****\*\/\/****\/\/*** {pyramid,ucsd}!ncr-sd!ncrwic!ksuvax1!paryavi

Yes and no.  I have used this drive extensively and i have the oem manual for
it .. unfortunately i am at work and it is at home :-(.  Anyway the interface
is indeed st506/412 no problems there.  But.. this drive uses an "embeded" or
"wedge" servo technique to determine the centerline of each cylinder.  Simply
stated,  this is 2 bursts of "data" at the end of every track that are 
aligned slighly to the left and right of the center line.  The drive uses these
to figure out if it is in the center of the track (drive says to itself ... 
"self;  the left signal is stronger than the right signal .. golly gee i must 
be to the left of the center line .. adjust the position on the next 
revolution so i am centered").  Anyway, what this means is that the drive 
must record its information in slightly less than one full circunference
of a track to allow for the "wedge" information.  And your controller MUST
know how to deal with that situation.  Some controllers don't (xebec 1410),
some controllers do (xebec 1410A ... don't ask I just know) by setting a 
special bit in a status word, and some controllers figure it out for themselves
such as a controller in a Convergent Technologies Mini Frame.  I suspect that
most of the standard AT type controllers (WD1003 etc) will firgure it out
but i can't say for sure.  One thing is sure: if the controller can't deal
with the "wedge" I sure as heck isn't going to work.  

I don't remember all of the tech specs for this drive except that it will
format to about 35mb (at 17 sectors 512bytes per sector) and is spec'd at
40ms per track.  Also it is the same drive that DEC sells as an RD52A.
If you call Quantum and ask for a Q540 OEM manual they will send you one 
for free.  If you want the specs send me mail or post here or call me at home
some night (weekdays after 7:00 pm at 412-367-7308)  and i will give them to 
you.

Good luck
Eric (the red) Liber