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DOS 6 comes with a data compression program called DoubleSpace. It may almost double the size of your hard drive by compressing files. Compression programs use a kind of shorthand so that repeated data is stored in less space. Actually, a DoubleSpaced compressed drive is a single file on an uncompressed drive. Such files are called Compressed Volume Files (CVF). DoubleSpace is invisible to your programs. You can use DoubleSpace on both hard disks and floppy disks. HOWEVER, DON'T USE IT WITHOUT READING THE CAUTIONS BELOW.


  1. A DoubleSpaced hard drive is more likely to give trouble than an uncompressed drive. If you have plenty of room on your hard drive, don't install DoubleSpace. You will be much better served with a large hard drive that is not compressed. To date, there have been many reports of problems with DoubleSpace. If you need more room, my advice is to buy another or a larger hard drive.
  2. If you plan to use DoubleSpace, you should read the README.TXT file in the C:\DOS directory.
  3. You should not use DoubleSpace if your drive is already compressed with another compression program. You could lose all your files!
  4. If you run DoubleSpace, you will not be able to uninstall DOS.
  5. You cannot uncompress a drive that has been DoubleSpaced. Microsoft did not provide an uncompress command.
  6. DoubleSpace can compress a drive to a maximum of 512 megabytes.
  7. When you run DoubleSpace, DOS creates an extra drive. If you compressed drive C, you would then have a small uncompressed drive (perhaps drive H, it depends on your hardware). Be careful not to move or delete any of the files in this new uncompressed drive, or it could result in the data loss of your entire C drive. The files on this uncompressed drive are: IO.SYS, MSDOS.SYS, DBLSPACE.BIN, DBLSPACE.INI, and DBLSPACE.000. These files are Hidden and have a Read-Only attribute. To determine where DOS placed this uncompressed drive, type DBLSPACE/INFO <ENTER> after you install DoubleSpace. If you want to see these hidden files, you can use the DIR/A command. Remember, don't fool with these files!
  8. Before you use DoubleSpace to compress a drive, it is a good idea to back up your drive. NOT DOING SO COULD RESULT IN A PERMANENT LOSS OF ALL YOUR DATA.
  9. If you plan to install Windows, you should do it before you run DoubleSpace. Windows has a swap file that should be stored on an uncompressed drive. If you install Windows first, DOS will automatically take care of this for you.
  10. Disable any screen blankers before you run DoubleSpace.
  11. DoubleSpace cannot be run from Windows. DoubleSpace should be run only at the DOS prompt.
  12. Use the CHKDSK command to keep an eye on any DoubleSpaced drive. This command will often inform you when (or if) there is trouble.