DPROTECT - A disk protection scheme, Version 1.03 - 07/07/86

Copr 85-86, GEE WIZ(tm) Software Company, ALL RIGHTS RESERVED

Written by Gee M. Wong


NOTICE
------

DPROTECT may not be sold, used in a commerical environment, nor packaged with
any commerical product without prior written permission from GEE WIZ Software
Company.

DPROTECT may be distributed freely at no cost to the recipient. User support
for this utility may be best obtained by notifying GEE WIZ. NO SUBSCRIPTION IS
NECESSARY FOR USER SUPPORT.

If you feel that this utility is of value, please feel free to send your
voluntary contribution of $5.00 to:


Gee M. Wong
6 South Woodland Avenue
East Brunswick, NJ 08816


DESCRIPTION
-----------

DPROTECT may be used to write protect one or more floppy disk drives and all
fixed disk drives from Trojan Horse programs. DPROTECT may not be able of
protecting any RAM disk or external/network drives which do not resemble a
standard IBM floppy disk or hard disk drive.

DPROTECT has been test on a 3270-PC, XT/370, and AT/370 equipped with the
standard floppy disk and hard disk drives and controllers supplied by IBM,
using PC-DOS(tm) 2.1, 3.1, and 3.2.

When DPROTECT is executed, it will install a portion of itself as a resident
program, and it will redirect all invocations of BIOS level interupt 13H to its
resident code, which will validate all disk I/O requests.

Everytime an I/O request is made, DPROTECT will intercept the request at the
BIOS level, interupt 13H, and determine if the request is being made against a
drive it is protecting. If the request being performed is against a protected
drive, then the requested is analyzed to determine if the request is for a
service which will modify any data on that drive. When both conditions are
present, DPROTECT will display a message on the screen informing you of a
detected update request, and its intend on performing a COLD system reboot.
Then DPROTECT will pause, to allow you enough time to read the error message,
and wait for you to type any key before rebooting your PC.

For your protection, a COLD system reboot is always performed whenever a drive
is illgeally access; you can never know what time bombs a Trojan Horse Program
will leave behind in your PC's RAM or device registers.

This version of DPROTECT is only able to intercept an I/O request at a BIOS
level. IT IS NOT ABLE TO SAFEGUARD AGAINST PROGRAMS WHICH ACCESS CODE IN ROM
THROUGH ITS ROM ADDRESS. Hopefully, an interpertive version of DPROTECT will
be available to circumvent those Trojan Horse programs which attempts to
execute ROM code directly.

Once the fixed disk drives or diskette drives are protected, the only way to
remove the protection is to reboot DOS.


USAGE
-----

To protect a disk or diskette, use the command:

DPROTECT drive

where drive is the letter of the drive you would like to have write protected,
or '*' for all drives.


DISCLAIMER
----------

The author has taken due care in developing and testing the effectiveness of
this utility, and makes no expressed or implied warranty of any kind with
regard to this utility. In no event shall the author or GEE WIZ Software
Company be liable for incidental or consequential damages in connection with or
arising out of the use of this utility.



HISTORY
-------

Version Date Description of Changes
-------------------------------------------------------------------------------
1.00 10/01/85 NONE. This is the original version.

1.01 10/11/85 Corrected code which perform system reboot to force a
COLD boot. The original version was accidently
released with code for performing a WARM boot.

1.02 11/07/85 Improved the code which scans the command line to
allow for multiple spaces, and to verify that a drive
letter was specified. If no drive letter was used, or
if the character specified is not a valid letter, then
a short description will be generated.

1.03 07/07/86 Documentation changes.


NOTES
-----

GEE WIZ is a trademark of GEE WIZ Software Company.
PC-DOS is a trademark of Microsoft Incorporated.
PC-DOS is a trademark of International Bussiness Machines.