MS-DOS 6.22 Help file
What's New in MS-DOS 6.22?
Welcome to Microsoft MS-DOS, the most widely used operating system for
personal computers. MS-DOS 6.22 improves on the safety and ease of use
provided by MS-DOS 6. The rest of this topic describes features new to
MS-DOS 6.22. For information about features included in both MS-DOS 6 and
MS-DOS 6.22, see the Welcome chapter of the MS-DOS User's Guide.
Changes and Enhancements to Disk Compression
MS-DOS 6.0 and 6.2 included DoubleSpace disk compression. MS-DOS 6.22
includes DriveSpace compression instead of DoubleSpace. DriveSpace appears
similar to DoubleSpace, but stores compressed information in a different
format. (If you are currently using DoubleSpace, you can continue to use it
with MS-DOS 6.22, or you can convert your DoubleSpace drives to DriveSpace
format. For more information, see ).
DriveSpace includes several new safety and convenience features that were
not in MS-DOS 6 DoubleSpace (note that if you are still using DoubleSpace
with MS-DOS 6.22, Setup has also made these enhancements to DoubleSpace):
DoubleGuard safety checking, which protects against data corruption by
verifying data integrity before writing data to your disk. If DoubleGuard
detects that the memory DriveSpace is using has been corrupted by another
program, it shuts down your computer immediately to minimize damage to
Although DoubleGuard is on by default, you can turn it off to save
memory. To do this, use the command, or turn off
the DoubleGuard option in the Options dialog (start DriveSpace, and then
choose Options from the Tools menu).
You can easily uncompress a DriveSpace drive or even completely uninstall
DriveSpace from memory. For more information, see
DriveSpace automatically mounts compressed floppy disks and other
compressed removable media -- even when Windows is running. Although
automounting is enabled by default, you can turn it off to save memory.
To do this, use the command, or turn off the
Automount option in the Options dialog (start DriveSpace, and then choose
Options from the Tools menu).
If you need to, you can bypass DriveSpace when you start your computer.
This makes troubleshooting easier and also temporarily frees memory for
use by other applications. For more information, see "Bypassing
DriveSpace" in the topic.
Other Safety Features and Enhancements
MS-DOS 6.22 includes ScanDisk, a utility that detects, diagnoses, and
repairs disk errors on both uncompressed and compressed drives. ScanDisk
can repair file system errors (such as crosslinks and lost clusters) and
physical disk errors. ScanDisk keeps a log of its repairs and enables you
to undo any of the changes it made. DriveSpace runs ScanDisk to check the
reliability of your disk before it begins compression. You can also run
ScanDisk yourself by typing SCANDISK at the command prompt. For more
information, see .
The MS-DOS extended-memory manager, HIMEM, automatically tests your
system's memory when you start your computer. This test can identify
memory chips that are no longer reliable. (Unreliable memory can result
in system instability or loss of data.) To turn off the memory test, add
the /TESTMEM:OFF switch to the command that starts HIMEM. For more
information, see .
Setup now configures SMARTDrive as a read-only cache by default. Even if
write-caching is enabled, MS-DOS does not display the command prompt
until SMARTDrive has written its cache to your disk. This prevents you
from turning off your computer before the data in memory is saved.
The , , and commands now ask you for confirmation
before copying a file over another file that has the same name. (However,
when issued from a batch file, these commands do not prompt for
confirmation before overwriting a file.)
Ease-of-Use Features and Other Enhancements
SMARTDrive now caches CD-ROM drives. (For this support to be enabled, the
MSCDEX program must be loaded before SMARTDrive. To find out if
SMARTDrive is caching your CD-ROM drive, type SMARTDRV at the command
prompt. If SMARTDRV lists the drive letter for your CD-ROM drive, the
drive is being cached. For more information, see .
You can now bypass or carry out individual commands in your AUTOEXEC.BAT
and other batch programs. (In MS-DOS 6, this capability was limited to
your CONFIG.SYS file.) This feature makes it easier to isolate problems
when you are troubleshooting problems in your system configuration or in
To step through the commands in your AUTOEXEC.BAT file, press F8 when
your computer starts. For more information, see "Bypassing CONFIG.SYS and
AUTOEXEC.BAT Commands" in the topic. To step
through other batch files, use the command.
The command now uses your hard disk as an interim storage
area, which makes copying from one floppy disk to another faster and
Microsoft Defragmenter makes better use of your computer's extended
memory, so it can now defragment much larger disks and disks containing
many more files and directories. For more information on running
Defragmenter, see the command.
The output of the DIR, MEM, CHKDSK, and FORMAT commands is much easier to
read, since it now includes thousands separators when displaying numbers
greater than 999. For example, "1000000 bytes free" now reads "1,000,000