Path: utzoo!attcan!uunet!munnari.oz.au!bruce!merlin!paulg
From: paulg@bhpmrl.oz.au (Paul Gallagher)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: SOME DRIVE TYPE QUESTIONS
Keywords: compuadd disk
Message-ID: <1664@merlin.bhpmrl.oz.au>
Date: 29 Oct 90 11:01:36 GMT
References: <1990Oct27.211413.15998@cbnewsl.att.com>
Sender: usenet@bhpmrl.oz.au
Lines: 29

Ah! The omnipresent 3650! This disk's a bit of a maverick as far
as getting the system configured is concerned. The IBM AT CMOS
drive table contained 15 entries. It sounds as though Miniscribe
took the easy path and documented the 3650 as type 3 because (even
though the parameters don't match properly) its the nearest match
you'll find!
The first 15 entries of the drive table on most machines match
the original AT table, but additional entries are generally
proprietary. The bottom line is that the 3650 doesn't have a
standard type number.
Regarding precomp: 300 is actually the documented pre-compensation
for the 3650. This is the cylinder that the write current is stepped
up in order to account for the shorter linear sector size as you
approach the centre of the disk. Starting the pre-comp further out
(i.e. at 128) thus shouldn't have an bad side-effects (whereas a 
higher pre-comp could have exposed you to data corruption problems.

Hope this has been of some help.

Regards, Paul.


     /\/\       Paul Gallagher, PC Support Officer,
    / / /\      Computer Systems Group,
   / / /  \     BHP Melbourne Research Laboratories
  / / / /\ \    245 Wellington Rd Mulgrave Vic 3170 AUSTRALIA
  \ \/ / / /    Phone : +61-3-560-7066,  Fax : +61-3-561-6709
   \  / / /     ACSnet  :  paulg@bhpmrl.OZ.AU        
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