Consider, for example, an individual who uses a wheelchair to get from place to place. A table set to a height of thirty inches may satisfy this individual's access requirements by ensuring that there is sufficient clearance height between the table and floor to accommodate the wheelchair. The wheelchair user can then move to a comfortable distance from the computer to do his or her work. While a table is admittedly low tech, it can mean the difference between an accessible and inaccessible computing environment. The use of a relatively commonplace alternative pointing device, like a trackball, can also make a huge difference for individuals with disabilities.
Many people find it difficult to execute the wide arm movements required to use a mouse.
The only requirement for manipulating a trackball is moving one's fingertips. Many disabilities cannot be accommodated as easily. Information is displayed graphically so that we can interpret and process it visually. However, for those without vision or with significantly impaired vision, the monitor may provide no helpful information. Blind computer users complete computer-related tasks assisted by a multimedia card that outputs a choir of synthesized human voices speaking at varying rates and pitches.