DoubleDisk 2.5

First released in 1989, DoubleDisk was the first real-time drive compression product for DOS. It is a fairly no-frills program and sticks to what it does best. It was relatively low cost compared to its later competitors.

DoubleDisk works by creating a hidden file on the regular hard drive that is then presented to the system as an extra drive letter. Files copied in to this drive are invisibly compressed and decompressed. Applications do not have to take any special action or include any specific support.

DoubleDisk is notable as its compression technology was licensed by Microsoft for use in MS-DOS 6.0's DoubleSpace.

It competed with other compression tools such as Stacker, SuperStor, and Expandz! Plus

Vertisoft later released an add-on for DoubleSpace called SpaceManager.

Also see: Software Spotlight: Drive Compression tools

Screenshots

Release notes

Note: Version 2.5 is not backwards compatible with earlier versions.

2.5 was followed by DoubleDisk 2.6, then by an immediate jump to "DoubleDisk Gold 6.0". 6.0 Gold added better removable media support, faster performance, and support for EMS, XMS, and UMB memory, but was best suited to DOS 5.0 or earlier.

Wanted: DoubleDisk 1.x, 2.0, 6.0 Gold.