Double Tools for DoubleSpace


Double Tools for DoubleSpace is a software utility released in 1993 by the Menlo Park-based company Addstor, Inc. The utility functioned as an add-on to the disk compression software DoubleSpace, supplied with MS-DOS 6.0, adding a number of features not available in the standard version.

Features

Most of the Double Tools utilities worked from Microsoft Windows, providing a graphical view and control panel of the compressed drives on the computer. Double Tools also contained a number of disk checking and rescue/recovery utilities. Some of the included utilities were called Silent Tools. One of the unique features of its time was the capability to defragment a DoubleSpace compressed drive in the background.
Some of the features, including the background defragmentation capability, required the user to let Double Tools replace the standard compression driver for MS-DOS with one developed by Addstor, claimed to be 100% compatible with DoubleSpace and the Microsoft Real-Time Compression Interface introduced in MS-DOS 6.0. This driver added a number of extra features, such as the use of 32-bit code paths when it detected an Intel 80386 or higher CPU, caching capabilities and - in addition to its supporting the use of the Upper Memory Area - also permitted the use of Extended Memory for some of its buffers.
Other features provided by Double Tools was the ability to have compressed removable media auto-mounted as they were used. Although this capability was later introduced into the standard version of DoubleSpace found in MS-DOS 6.2, Double Tools also had the capability to put a special utility on compressed floppy disks that made it possible to access the compressed data even on computers that didn't have DoubleSpace.
Another interesting function was the ability to split a compressed volume over multiple floppy disks, being able to see the entire volume with only the first disk inserted. It was also possible to share a compressed volume with a remote computer.