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 <DBLSPACE>).

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
   your data.

   Although DoubleGuard is on by default, you can turn it off to save
   memory. To do this, use the <DRVSPACE /DOUBLEGUARD> 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
   <DRVSPACE /UNCOMPRESS>.

*  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 <DRVSPACE /AUTOMOUNT> 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 <CONFIG.SYS Commands> 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 <An Introduction to ScanDisk>.

*  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 <HIMEM.SYS>.

*  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 <MOVE>, <COPY>, and <XCOPY> 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 <SMARTDRV>.

*  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
   batch programs.

   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 <CONFIG.SYS Commands> topic. To step
   through other batch files, use the <COMMAND /Y> command.

*  The <DISKCOPY> command now uses your hard disk as an interim storage
   area, which makes copying from one floppy disk to another faster and
   easier.

*  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 <DEFRAG> 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
   bytes free."