On-Screen Keyboards
As the name suggests, this input mechanism is to make selections from a keyboard which is displayed on the screen, by a software package. Selections are made by mouse clicks from trackballs, mice or pointing devices or by dwelling on the keyboard location for a pre-established period of time. The disadvantage is the screen real estate lost to the keyboard- a large monitor is helpful. The advantage is the lack of movement required- the individual does not need to take their eyes off the screen to look at a keyboard. On-screen keyboards generally operate transparently with applications.
On-screen keyboards usually include sticky key features and some colour coding. Some incorporate word prediction or voice output for face-to-face communication. Some of the augmentative communication softwares offer programmable on-screen keyboards for those with literacy needs. Some keyboards have versions which can be operated by single or dual switches, becoming, in essence, scanning keyboards- more on scanning later. Keyboards vary significantly in price, with additional features like voice output, word prediction or scanning at marketed at higher prices.