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From: maschler@sonia.math.ucla.edu
Newsgroups: comp.sys.ibm.pc.misc
Subject: The effect of heat on diskettes
Message-ID: <174@kaos.MATH.UCLA.EDU>
Date: 27 Jul 90 00:09:35 GMT
Sender: news@MATH.UCLA.EDU
Reply-To: maschler@MATH.UCLA.EDU ()
Organization: UCLA Mathematics Department
Lines: 30

Some time ago I posted here a question concerning the following erratic
behavior of my Compaq SLT 286: Quite often, I would not be able to
read diskettes -- even those formatted and written into by this
computer, but a few hours later, or a few days later, the diskette
would be read normally. (Sometimes nothing would help...) I received 
several replies, but none actually explained this strange behavior.

Recently, Brian Aslakson suggested that the condition has to do
with temperature variability, and suggested that I should always
format, read and write into my diskettes when the computer is warm.m

Here is the scientific explanation that Brian added:

"....Second, heat generated can warm and therefore expand
floppy disks in the internal drive.  If a file is written to the
disk in this condition--say on a hot summer afternoon after your 
machine has been on for several hours--it can disappear
the next morning when you turn your machine on.  The disk drive
will be searching for a track that moved a little during the night
as the disk cooled.  (If this happens to you, the file can most
likely be recovered by letting the machine--and therefore the disk--
warm up for a few hours and then trying to reread it.)"

  	--From "Fans, pro and con", Chapter 7 (Miscellaneous hardware),
	  p. 277, "The Macintosh Bible" 2nd ed., Naiman et al.
	  (the above section attributed to Naiman, Coleman, and Swain)

Brian Aslakson

aslakson@cs.umn.edu