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From: dkim@maui.cs.ucla.edu (Dong Hun Kim)
Newsgroups: comp.sys.ibm.pc
Subject: Re: 3.5" 1.44/720K drive question
Summary: Compatibility 3.5" 1.44/720k
Keywords: 3.5" drive, 1.44M, 720K
Message-ID: <22204@shemp.CS.UCLA.EDU>
Date: 24 Mar 89 18:48:25 GMT
References: <8168@xanth.cs.odu.edu> <22063@shemp.CS.UCLA.EDU> <10121@cit-vax.Caltech.Edu>
Sender: news@CS.UCLA.EDU
Reply-To: dkim@cs.ucla.edu (Dong Hun Kim)
Organization: UCLA Computer Science Department
Lines: 21

In article <10121@cit-vax.Caltech.Edu> tim@cit-vax.UUCP (Timothy L. Kay) writes:
>In article <22063@shemp.CS.UCLA.EDU> dkim@cs.ucla.edu (Dong Hun Kim) writes:
>>How to install the switch :
> [...]
>
>If I trick my drive into writing 1.44M on a 720K disk, and then I give
>it to somebody who has not defeated the sensor in his drive, can he
>read the disk?  (In other words, does DOS set the density for reading
>by looking at the hole, or just the density when formatting?)
>
>Tim

This is a good point, which I forgot to mention in my previous posting.
The answer is : NO, he will not be able to read it.
Because his drive will still look for the hole, and if there is no
hole, it assumes as 720K.

EXCEPTION : IBM-PS/2 drive does not use probe, 
            so it can format and read both densities.

Dong Kim