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From: asgard@cpro.UUCP (J.R. Stoner)
Newsgroups: comp.sys.ibm.pc
Subject: IBM media foulup (was IBM PS/2)
Message-ID: <351@cpro.UUCP>
Date: Wed, 26-Aug-87 02:19:16 EDT
Article-I.D.: cpro.351
Posted: Wed Aug 26 02:19:16 1987
Date-Received: Sat, 29-Aug-87 06:15:00 EDT
References: <1338@dataio.Data-IO.COM> <3735@well.UUCP> <1426@chinet.UUCP>
Reply-To: asgard@cpro.UUCP (J.R. Stoner)
Organization: CompuPro/VIASYN Corporation, Hayward, CA
Lines: 33
Keywords: ANSI IBM media disks
Summary: You should not defeat media protection.

In article <1426@chinet.UUCP> ward@chinet.UUCP (Ward Christensen-) writes:
>Regarding the hosed-up control and caps-lock keys on "enhanced"
>  Re: 720K diskettes, etc: I buy generic 720K'ers from 1-800-USA-FLEX, and
>was VERY surprised they formatted to 1.44M first time I tried it on
>a PS/2-50!  I fully expected the "density identification hole" on the
>2M diskettes to be read by the drive, but, sigh, no.

This was confirmed this week in EE Times.  IBM deliberately designed out the
ANSI media switch/detector on their 3.5" drives.  A major flaw in my opinion
as then one could defeat the required protection as you say you did.  You
could very well format a 1Mb disk with a 2Mb format, but the media process
requires a different write current than the 2Mb disk since the media has a
higher coercivity.  The main purpose of the ANSI switch was to automagically
flop the write current when the media switch is active.  I suspect that when
you have done this for a while you will see that when temperature changes
sufficiently around a mis-formatted disk you will not be able to read the
flux changes off the diskette properly.
-- 
"To prevent having to tell fools to RTFM don't let on you WTFM to begin with."
J.R. Stoner	asgard@cpro.UUCP    asgard@wotan.UUCP
P.S. I help CompuPro make computers.  They do not help me make my opinions.