the surface of the medium. However, since in many cases, the medium was housed in a removable cartridge or pack and since air filtration was comparatively crude, crashes were fairly frequent and invariably expensive. Laptops Head crashes have been a frequent problem on laptop computers since they first incorporated hard drives, since a laptop computer is more liable to be dropped or jostled than a stationary machine. This has led to the development of protective technologies that "park" the head at a safe distance from the disk when sudden motion, such as that of a dropped computer, is detected. Active Hard Disk Protection software and sensors began appearing in laptops in 2003 with IBM introducing it in their ThinkPad line of laptops, becoming common around 2009 with the introduction of Windows 7. These drives are also designed to "self-park" during sudden power loss, which has reduced the incidence of head crashes. With the popularization of solid-state drives, which have no head or disk, the head-crash issue has been nearly eliminated in modern laptops. See also Active hard-drive protection Bad sector Click of death References Hard disk drives Semiconductor device defects Technological failures