Using DiskLock PC with MS-DOS 5.x or 6.x (73444)
The information in this article applies to:
• Microsoft MS-DOS operating system 5.0
• Microsoft MS-DOS operating system 5.0a
• Microsoft MS-DOS operating system 6.0
• Microsoft MS-DOS operating system 6.2
This article was previously published under Q73444
This article contains information about using DiskLock PC versions 1.01 and
1.02 from Fifth Generation Systems with MS-DOS version 5.0 or 6.0.
DiskLock is drive-locking software. Once installed, it modifies the master
boot record and installs the device driver, DISKLOCK.SYS, in the CONFIG.SYS
file. According to Fifth Generation Systems, DiskLock PC is compatible with
MS-DOS 5.0 or 6.0 as long as CONFIG.SYS contains the following lines:
DEVICE = C:\DOS\HIMEM.SYS
DOS = HIGH
If either of these lines is not present, DiskLock PC may not load or may
generate a series of error messages.
According to Fifth Generation Systems, the recommended steps to install
MS-DOS 5.x or 6.x on a machine with DiskLock PC are:
• Uninstall DiskLock.
• Install MS-DOS 5.0 or 6.0.
• Install DiskLock.
DiskLock PC allows locking of floppy drives, individual partitions on
a hard drive, files, and directories.
DiskLock PC modifies the master boot record so that the first thing the
system does is look for the DISKLOCK.SYS device driver. If such a driver
cannot be loaded, the machine is unusable. You may be able to access the
drive(s); however, all data on the drive(s) or locked files or directories
is encrypted. To verify whether you can properly access the drive, issue
the DIR command. The screen displays scrambled information that cannot be
read. This is due to the encrypting in effect by DiskLock. No data is lost,
however, and the hard drive is still operable as long as you load DiskLock
If you use FDISK to view the partition(s) information, the locked drive
will show as a XENIX partition. Even though such a partition can be deleted
in MS-DOS 5.0 or 6.0, doing so is not recommended because your data is
still encrypted and you cannot access it.
Loading MS-DOS low or falling to install HIMEM renders the machine
unusable. If you cannot reload DiskLock, the only way to be able to
use the hard drive is to low-level format it. If DiskLock hangs during
installation after installing MS-DOS 5.0 or 6.0, you cannot use it.
If you use DiskLock PC with MS-DOS 6.0, you cannot use the MEM command to
display what is loading in the Upper Memory Block (UMB) area. Upper memory
is displayed as 0. DiskLock does not prevent the use of the UMB; it just
prevents the information from being shown when you issue the MEM command.
DiskLock PC is manufactured by Fifth Generation Systems, a vendor
independent of Microsoft; we make no warranty, implied or otherwise,
regarding this product's performance or reliability.
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