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From: ezk@cunixe.cc.columbia.edu (Erez "HWank1" Zadok)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: Making a floppy drive ignore high density hole
Keywords: 3.5 drive, HD, DD, switch
Message-ID: <1990Jul19.193954.29829@cunixf.cc.columbia.edu>
Date: 19 Jul 90 19:39:54 GMT
References: <11547@ingr.com> <1990Jul19.021714.10040@world.std.com> <803@digi.lonestar.org>
Sender: news@cunixf.cc.columbia.edu (The Daily News)
Reply-To: ezk@cunixe.cc.columbia.edu (Erez "HWank1" Zadok)
Organization: Columbia University Center for Computing Activities
Lines: 47

In article <803@digi.lonestar.org> mfrohman@digi.lonestar.org (Matthew Frohman) writes:
> I have a pair of those floppy drives which insists on detecting for me,
> if there is a hole in my floppy disk.  I would like to install a toggle
> switch to enable/disable the detector.  Ideally, I would like it to have
[...]
> Anyone out there done this already?  A detailed description would be
> appreciated, since I do not do this sort of thing often, and I don't
> want to destroy my computer.
[...]
> 		Thanks in advance,
> 		Matthew

A while back I was seeking a software solution to the same problem, via the
DRIVPARM option of CONFIG.SYS.  I dumped the idea and decided to (finally
:-) utilize my 5 years of EE studies and put a switch instead.  I opened my
machine and after a few screws (no jokes please) got to the circuit board of
my 3.5 drive (I think it is a Mitsubishi) where I found a small switch on
the front right corner of the board.  I soldered out that switch.  Put a
hole in the left front panel of my drive and made sure the location of the
external switch did not interfere with anything inside.  I then placed a
simple two-position on/off switch where I made the hole, and ran two 22
gauge wires from the external switch to the previous location of the
internal switch. You have to make sure the wires you run don't interfere
with the moving parts inside the drive.  Of course I could have put the
switch on the right side, or anywhere else on my box.  That's your choice.
If your drive is of a different make, the instructions may vary.  The
location of the screws may be different, etc.

Now, if the external switch is in one position, I can read and format DD
disks, and if it's in the other position, I can read DD or HD and format HD.
I found that to be most convenient esp. when you're short on disk space.  I
haven't had any problems since (5-6 weeks now.)  Note however that
formatting as HD on a DD disk might not yield a full 1.44Mb and should not
be used for long term storage of files since these disks tend to go bad
often; but for short periods of time formatting DD as HD is fine.

I would guess that there might be a way to have a switch that would also
have an "auto sense" mode, but I didn't really want to complicate matters
too much.  I found the current setup adequate.  After I format my floppies,
I put the switch in the one mode that can read both HD and DD.

Hope this helps.

Erez.
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