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From: brucer@gvgpsa.UUCP (Mitch Hendrickson)
Newsgroups: comp.sys.ibm.pc
Subject: Adding 3.5" drive to PCjr
Message-ID: <507@gvgpsa.UUCP>
Date: Wed, 29-Jul-87 02:30:01 EDT
Article-I.D.: gvgpsa.507
Posted: Wed Jul 29 02:30:01 1987
Date-Received: Fri, 31-Jul-87 01:36:43 EDT
Organization: Grass Valley Group, Inc., Grass Valley, CA
Lines: 25

I am about to undertake a project and could use a little advice from some PC
guru out there:

I have a PCjr with 640k and provision for another drive.  I would like to
make this drive a 3.5" 720k disk.  The device driver packaged with the
system (ie memory + second drive mod) for enabling the second drive simply
bumps the equipment configuration word drive count and reboots the system,
to enable DOS to recognize that I have two drives.

I have been thinking of two options:

1)	Leave DOS thinking I only have 1 drive (ie A and B both point to the
same physical drive) and write my own device driver for the 3.5".  Don't
worry - I have intimate experience with the controller from another project.

2)	Somehow (and this is where I might need some help)
patch/modify/otherwise inform DOS that drive B: is of a different format.

Does anyone out there have any comments or suggestions, and especially in
the case of option 2), any pointers that might help me out?

				AdvTHANXance,

				Mitch Hendrickson
				(...tektronix!gvgpsa!brucer)