5.3 Impairment of physical functions.

5.3.4 Devices for computer access.

In this chapter devices for computer access are ordered and described by criterions of the products and by criterions of basic principles.  Links lead you to databases, producers and resellers of computer access products.  For an explanation of basic principles of computer access, please see "5.3.1 Impairment of physical functions: Basic principles of input devices".

This chapter is subdivided into:

5.3.4.1 Direct typing/keyboards,

5.3.4.2 Pointing devices,

5.3.4.3 Sensors and switches,

5.3.4.4 Output devices.

You find a short description about "keyboards for handicapped persons", "pointing devices", "buttons and sensors" at the "computers help to heal"-site of Siemens.

5.3.4.1 Direct typing/keyboards.

Operating of a standard keyboard requires enough force and endurance in arm and hand as well as a sufficient range of movement. Additionally it requires some more precisely motor functions in order to aim, point at and typing a single key.  In general there are several possibilities if operation of a standard keyboard is restricted:

• adjustment - the present keyboard could be adjusted either on the software side in the OS or if possible on the hardware side at the keyboard itself (see: "Unit 1: Basics of computer technology for AT professionals"; "Unit 3: Requirements on computer users"; "Unit 4.2: General Trends / Mainstream: Accessibility Features in the Microsoft Windows® Family"),
• adaptation - the working place could be adapted by choosing additional aids,
• alternative hardware - the size of the whole keyboard or of the keys could be redefined and an alternative could be chosen,
• alternative input - the body part which could be used can be redefined and additionally for this it could be necessary to choose an alternative keyboard. 

You see an example of different steps in the decision process of choosing a keyboard in Unit 6 Assessment of individual needs.

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5.3.4.2 Pointing devices.

The same as mentioned for a standard keyboard applies to the standard pointing device, the mouse.  Controlling a standard mouse even requires enough force and endurance in arm and hand as well as a sufficient range of movement.  Additionally it requires some more precisely motor functions, for example to drag something it is necessary to move the mouse and to press a mouse-key at the same time.  Here again it is possible to adjust the mouse settings, to adapt the working place or to choose an alternative hardware or an alternative input: 

• adjustment - the present pointing device could be adjusted on the software side in the OS (see: "Unit 1: Basics of computer technology for AT professionals"; "Unit 3: Requirements on computer users"; "Unit 4.2: General Trends / Mainstream: Accessibility Features in the Microsoft Windows® Family").  Speed and acceleration is adjustable as well as the appearance and size of the mouse cursor.  Special mouse software offers further helpful adjustments. 
• adaptation - the working place could be adapted by choosing additional aids,
• alternative hardware - the size of the standard mouse or of the mouse-keys could be redefined and an alternative could be chosen,
• alternative input - the kind of pointing device and/or the body part which could be used can be redefined and additionally for this it could be necessary to choose an alternative mouse or another pointing device. 

Show product groups.

5.3.4.3 Sensors and switches

Sensors and switches can be used in addition to the standard input devices - keyboard and mouse - or instead of this standard input devices.  As an additional device sensors and switches which are adapted to the disabilities or rather the abilities usually replace special keys like the mouse keys, the modifier keys or the power switch of the computer.  For computer access mostly sensors and switches are used in combination with virtual keyboards and scanning methods.

• adjustment - dependent on the chosen sensor/switch and dependent on the software which should be controlled by the sensor/switch,
• adaptation - the working place could be adapted by choosing additional aids and special mounting systems,
• alternative hardware/alternative input - the kind of sensor/switch and/or the body part which could be used can be redefined and additionally for this it could be necessary to choose an alternative switch input device. 

For this please have a look at chapter 3 "Choosing switches" of the "ACE Centre Switch Access Course".

5.3.4.4 Output devices.

For a description of the standard output devices please see "Unit 1: Basics of computer technology", "Unit 3: Requirements on computer users" and "3.2 Input and output devices of a standard personal computer".  

Special output devices used by users with low vision or by blind users are:

• braille printers,
• braille display,
• speech output,
• magnifying systems.