Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!bu.edu!wang!saturn!martin
From: martin@saturn.uucp (Martin J. Schedlbauer)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: Can I Low Level Format my MFM drive with 17 < SECTORS < 26 ?
Message-ID: <1991Mar19.235454.249@saturn.uucp>
Date: 19 Mar 91 23:54:54 GMT
References: <5832@trantor.harris-atd.com>
Reply-To: martin@saturn.UUCP (Martin J. Schedlbauer)
Organization: Martin Schedlbauer, Billerica, MA 01862 (USA)
Lines: 32

In article <5832@trantor.harris-atd.com> sonny@trantor.harris-atd.com (Bob Davis) writes:
>
>	I know that MFM normally uses 17 Sectors/Track and RLL uses 
>26 Sectors/Track. But is there a fundamental reason I cannot low
>level format my MFM drive to 20 Sectors/Track, say, in an attempt
>to increase drive capacity? Does the MFM controller FORCE the
>use of 17 S/T and the RLL controller 26 S/T or might they do whatever
>they are told by the Low Level Formatter program?
>
I have in the past formatted a Maxtor XT1085, which is a 17 sector/track
MFM hard disk, to 18 sectors/track. I tried more but the low-level format
failed at higher than 18 settings.

It'll work, but chances are very high that your harddisk controller BIOS
can't handle anything but 17 sectors/track. That typically means that the
track buffer only holds 17 sectors worth of data. For a 1:1 interleave
that means one revolution to read one track. If you increase the drive
capacity to 18 sectors per track you'll read 17 + 1, i.e. an extra 
revolution is needed to read a single track. Ergo, your read times increase
almost two-fold.

Of course, at 18 or more sec/track, you mau experience media failure soon...

	...Martin



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