Keyboard modifications
Keyboard emulation of mouse functions
Description
With additional software, either a standard keyboard or an alternative keyboard can be used to perform mouse functions. Certain keys (usually on the numeric keypad) will control mouse movements and facilitate click and drag functions.
Advantages
This software is important for people who use pointer sticks to operate computers. It is also helpful to those with poor fine-motor coordination, which can make mouse control difficult and frustrating.
Disadvantages
Good visual skills are required. Some of the flexibility and spontaneity of mouse and trackball use is lost. If required, alternative keyboards can be very expensive.
Software options to modify keyboard functions
Description
The action of keys can be modified through software to reduce errors and/or to allow easier operation. The following options are commonly available:
Repeat rate can be reduced or eliminated. That is, when a key is held down, more time will be required before the character is repeated. This can be helpful in preventing accidental multiple presses of a key.
The time for which a key must be held before it acts can be increased over a quite wide range. This reduces the risk of accidental key presses. It can be helpful to people who have poor motor control of fingers and to those who use a pointer stick to operate the keyboard. The feature is often called ‘slow keys’.
Modifier keys-shift, alt and control-can be pressed in sequence before the key to be modified, rather than simultaneously. This facility is commonly referred to as ‘sticky keys’. It is an important feature for people who have difficulty pressing two keys at once. Pressing the shift key twice in succession will act as a shift lock. All following characters will be uppercase until the shift key is pressed again to release the shift lock. In many cases, but not all, the caps lock key can serve the same purpose.
The numeric keypad can be used to emulate the mouse. For people who have difficulty controlling a conventional mouse, keys on the numeric keypad can be used to move the mouse horizontally, vertically and diagonally. Left and right mouse buttons are also available.
There is also a facility called ‘serial keys’. This allows external equipment such as augmentative communication devices to be used to control the computer via the serial port.
Advantages
This is an inexpensive and often effective means of tailoring a keyboard to the needs of an individual. It can overcome problems caused by the user having limited arm movement, not being able to press two keys simultaneously, holding down keys longer than normally allowed or bumping incorrect keys. Well-designed software (certainly all examples listed below) can be easily toggled on and off. That is, a person requiring the adaptations can share a machine with people who do not require them with little or no inconvenience to any user.
Disadvantages
Some (very minimal) extra computer memory is required. There can occasionally be conflicts with software.
Pointer sticks
Description
A short stick is used for pressing keys on a keyboard. It can be held in the hand or mouth or attached by a strap to the head. It is used in the hand to overcome problems caused by poor finger isolation. It is used in the mouth or attached to the head if hand movement is not possible.
Advantages
This is an inexpensive means of allowing operation of a keyboard when this would otherwise be difficult or impossible.
Disadvantages
Speed is necessarily slow. Effort, and perhaps additional hardware, is required to position the keyboard to maximise the user’s comfort. This involves ensuring that the user’s posture does not exacerbate the underlying disability.
