RAM Disk

History and operating system specifics

IBM added a RAM drive named VDISK.SYS to PC DOS (version 3.0) in August 1984, which was the first DOS component to use extended memory. VDISK.SYS was not available in Microsoft's MS-DOS as it, unlike most components of early versions of PC DOS, was written by IBM. Microsoft included the similar program RAMDRIVE.SYS in MS-DOS 3.2 (released in 1986), which could also use expanded memory. It was discontinued in Windows 7. DR-DOS and the DR family of multi-user operating systems also came with a RAM disk named VDISK.SYS. In Multiuser DOS, the RAM disk defaults to the drive letter M: (for memory drive). AmigaOS has had a built in RAM drive since the release of version 1.1 in 1985 and still has it in AmigaOS 4.1 (2010). Apple Computer added the functionality to the Apple II series with ProDOS and, later, to Apple Macintosh with System 7's Memory control panel in 1991, and kept the feature through the life of Mac OS 9.