Path: utzoo!attcan!utgpu!news-server.csri.toronto.edu!rutgers!cs.utexas.edu!uunet!crdgw1!sixhub!davidsen
From: davidsen@sixhub.UUCP (Wm E. Davidsen Jr)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: RLL, sector remapping, and 1024 cylinders
Message-ID: <2043@sixhub.UUCP>
Date: 7 Oct 90 16:25:09 GMT
References: <90274.223047RFM@psuvm.psu.edu> <631@demott.COM>
Reply-To: davidsen@sixhub.UUCP (bill davidsen)
Organization: *IX Public Access UNIX, Schenectady NY
Lines: 27

In article <631@demott.COM> kdq@demott.COM (Kevin D. Quitt) writes:

|     Lots of disks have an odd number of heads for data, 

  True.

|                                                         because one head
| is used for sync tracks on a separate platter.  

  Often true. Some drives just don't have a head on the bottom or top
platter for marketing or total height reasons. Marketing=enough bad
platters on one side to make it worth useing them. No longer common, I
admit. 

|                                                 Use of this technique
| lets the disk write denser data because it can compensate for the
| variations in the speed of the platters.

  Not usually the case. For voice coil positioning the platter with the
sync track is used to position the head radially (to the correct track),
and this allows more tracks per inch rather than more fcpi (bytes per
track).
-- 
bill davidsen - davidsen@sixhub.uucp (uunet!crdgw1!sixhub!davidsen)
    sysop *IX BBS and Public Access UNIX
    moderator of comp.binaries.ibm.pc and 80386 mailing list
"Stupidity, like virtue, is its own reward" -me