SmartDrive (or SMARTDRV) is a disk caching program shipped with MS-DOS versions 4.01 through 6.22 and Windows 3.0 through Windows 3.11. It improves data transfer rates by storing frequently accessed data in random-access memory (RAM).
Early versions of SmartDrive were loaded through a CONFIG.SYS device driver named SMARTDRV.SYS. Versions 4.0 and later were loaded through an executable file named SMARTDRV.EXE, which could be run at user's discretion or at boot time via AUTOEXEC.BAT. However, SMARTDRV.EXE also includes a double-buffering driver that should be loaded through CONFIG.SYS. Version 4.0 also introduced 32-bit disk access and could reduce its footprint in conventional memory (the first 640 kilobytes of memory which was critical to DOS) by running in upper memory area (the 384 kilobytes of memory located beyond the conventional memory).
A cloaked variant of SmartDrive utilizing the Helix Cloaking API was available from Helix Software. On Intel 80386 processors, it could run in protected mode to reduce its footprint in conventional memory.
SmartDrive has been superseded by VCache, which was introduced in Windows for Workgroups 3.11 and carried over to Windows 95, 98/98 SE and ME. The main advantage of VCache over SmartDrive is its ability to adjust cache size dynamically. However, it tended to take too much RAM in Windows 95; this aspect was improved in Windows 98.
- "SMARTDrive Version History (Revision 2.1)". Support. Microsoft. 7 July 2005. Retrieved 17 June 2013.
- "SMARTDrive and 32-Bit Disk Access (revision 1.1)". Support. Microsoft. 16 November 2006. Retrieved 17 June 2013.
- "How to start the Setup program from MS-DOS in Windows XP (revision 6.0)". Support. Microsoft. 22 May 2013. Retrieved 17 June 2013.