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From: wrd@tekigm2.TEK.COM (Bill Dippert)
Newsgroups: comp.sys.ibm.pc
Subject: IBM 3.5 Drives
Message-ID: <2262@tekigm2.TEK.COM>
Date: Tue, 6-Oct-87 17:47:46 EDT
Article-I.D.: tekigm2.2262
Posted: Tue Oct  6 17:47:46 1987
Date-Received: Fri, 9-Oct-87 23:37:58 EDT
Organization: Tektronix Inc., Beaverton, Or.
Lines: 40
Keywords: 360k vs 720k

From: wrd@tekigm2.TEK.COM (Bill Dippert)
To: easdick@gpu.utcs.UUCP
Subject: Re: 720k format with MS-DOS ?
Newsgroups: comp.sys.ibm.pc
In-Reply-To: <1987Oct5.165618.20642@gpu.utcs.toronto.edu>
Organization: Tektronix, Inc., Beaverton, OR.

Apparently it is a bug, I ran into the same problem when I set up my XT with an
external 3.5" drive.  I have for my configuration:

     first 5.25" drive A:
     second 5.25" drive B:
     3.5" drive C: (360K for format purposes)
     hard disk D:
     3.5" drive E: and F: (720K for all purposes)

     (Don't ask why I made the hard drive D:, however, I thought that C: would
     work ok for the 3.5", but due to the bug, it does not.)

     Now, as to the bug:  note that I said that you cannot format disks using
     C: drive for anything other than 360K.  For all other purposes drive C: is
     720K, only when you try to format blank disks does it think that it is a
     360k drive.  Why is beyond me.  However, per IBM instructions, I set up
     two more disk drives as E: and F: (using the same 3.5" physical drive).
     These perform perfectly as 720K drives.  To do this, you need to setup in
     your config.sys file a statement --
     DEVICE = \DRIVER.SYS /D:2 /T:80 /S:9 /H:2

     (One of these will set up E:, two of them will set up E: and F:.)

     Apparently the default for the 3.5" disk is T:40, but there is nothing
     that I can find that shows how to change this default.  I thought that the
     device = statement would do this, but then I discovered that all it did
     was setup more diskdrive letters using the same physical drive.  The whole
     thing is ridiculous, another IBM "feature".  (The other possibility is
     that the default is D:1.)  T - track and D is single/double side disk, I
     think!
     I hope this helps, IBM's data sheets sure do not.

     --Bill--