Double Tools for DoubleSpace is a

software utility Utility software is software designed to help analyze, configure, optimize or maintain a computer. It is used to support the computer infrastructure - in contrast to application software, which is aimed at directly performing tasks that benefit ord ...

released in 1993 by the Menlo Park-based company Addstor, Inc. The utility functioned as an add-on to the

disk compression A disk compression software utility increases the amount of information that can be stored on a hard disk drive of given size. Unlike a file compression utility, which compresses only specified files—and which requires the user to designate ...

software

DoubleSpace DriveSpace (initially known as DoubleSpace) is a disk compression utility supplied with MS-DOS starting from MS-DOS 6.0, version 6.0 in 1993 and ending in 2000 with the release of Windows Me. The purpose of DriveSpace is to increase the amount ...

, supplied with

MS-DOS 6.0 MS-DOS ( ; acronym for Microsoft Disk Operating System, also known as Microsoft DOS) is an operating system for x86-based personal computers mostly developed by Microsoft. Collectively, MS-DOS, its rebranding as IBM PC DOS, and a few ope ...

, adding a number of features not available in the standard version.

Features

Most of the Double Tools utilities worked from

Microsoft Windows Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for serv ...

, providing a graphical view and control panel of the compressed drives on the computer (the utilities supplied with

MS-DOS MS-DOS ( ; acronym for Microsoft Disk Operating System, also known as Microsoft DOS) is an operating system for x86-based personal computers mostly developed by Microsoft. Collectively, MS-DOS, its rebranding as IBM PC DOS, and a few ope ...

only operated from DOS-mode). 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 (DBLSPACE.BIN) 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 In computer architecture, 32-bit computing refers to computer systems with a processor, memory, and other major system components that operate on data in 32-bit units. Compared to smaller bit widths, 32-bit computers can perform large calculation ...

code paths when it detected an

Intel 80386 The Intel 386, originally released as 80386 and later renamed i386, is a 32-bit microprocessor introduced in 1985. The first versions had 275,000 transistors CPU A central processing unit (CPU), also called a central processor, main processor or just processor, is the electronic circuitry that executes instructions comprising a computer program. The CPU performs basic arithmetic, logic, controlling, and ...

, caching capabilities and - in addition to its supporting the use of the

Upper Memory Area In DOS memory management, the upper memory area (UMA) refers to memory between the addresses of 640 KB and 1024 KB ( 0xA0000–0xFFFFF) in an IBM PC or compatible. IBM reserved the uppermost 384 KB of the 8088 CPU's 1024 KB ...

- also permitted the use of

Extended Memory In DOS memory management, extended memory refers to memory above the first megabyte (220 bytes) of address space in an IBM PC or compatible with an 80286 or later processor. The term is mainly used under the DOS and Windows operating systems. DOS ...

for some of its buffers (reducing the driver's total footprint in conventional and upper memory, albeit at the cost of somewhat reduced speed). Other features provided by Double Tools was the ability to have compressed removable media auto-mounted as they were used (instead of the user having to do this manually). 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 A floppy disk or floppy diskette (casually referred to as a floppy, or a diskette) is an obsolescent type of disk storage composed of a thin and flexible disk of a magnetic storage medium in a square or nearly square plastic enclosure lined w ...

that made it possible to access the compressed data even on computers that didn't have DoubleSpace (or Double Tools). 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 (and being prompted to change discs as necessary). It was also possible to share a compressed volume with a remote computer.

References

Hard disk software Data compression software DOS software Discontinued software {{storage-software-stub