Path: utzoo!attcan!ram
From: ram@attcan.UUCP (Richard Meesters)
Newsgroups: comp.sys.att
Subject: Re: 3B2 memory, floppy drive
Summary: Disk types and 3B2 drives.
Message-ID: <11036@attcan.UUCP>
Date: 17 Jan 90 17:28:44 GMT
References: <2182@becker.UUCP> <1069@icus.islp.ny.us> <860@red12.qtp.ufl.edu> <1990Jan17.062113.16770@robohack.UUCP>
Organization: AT&T Canada Inc., Toronto
Lines: 43

In article <1990Jan17.062113.16770@robohack.UUCP>, woods@robohack.UUCP (Greg A. Woods) writes:
> 
> Sorry Richard, but it's best if you DON'T try to use HD (high density)
> diskettes.  If I remember right they have been specially formatted
> during the manufacturing process in order to help the IBM PC/AT (and
> compatible) drives to seek to the centre of the track (remember when
> they cost $150 per box?  I sure do!).  This factory formatting is
> quite difficult to erase, and in any case, I've had no luck trying to
> use HD diskettes (when I was short of diskettes, I tried quite
> desparately, on three different 3b2/400's, and on a 3b2/300 to format
> some with no luck).
> 
> Your best bet for 3b2 floppy media is to use a known reliable brand of
> DS/DD (48tpi) diskettes (because they are cheap and easily available),
> and always format with error checking and write with verify.  All
> diskette media comes from the same cookie cutter.  The label
> identifies the degree to which it was tested.  Some manufactures
> downgrade the rating of cookies which fail the more stringent tests,
> and others simply junk the cookie.

Ah well, life goes on, doesn't it Greg?  I gave this a try and found out 
something very interesting.  It seems that the HD diskettes will format just
fine on my 3B2/600, but the 3B2/300 just doesn't seem to like them at all.
Very interesting, no?  Any comments, I thought that both drives were identical
(720K).  The front plates on the two drives are different, perhaps there is
a discrepancy in the specs from the different FDD manufacturers.

Anyway, the reason I suggested the HD disks is that DS/DD disks are only
specified for 360K usage, and I had concerns with data integrity when you 
try to format them on a 720K drive.  I suppose if you limit yourself to a 
known manufacturer of disks, you are reasonably safe with the DS/DD disks.
Stay away from the cheap no-names though.

Regards,

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