Switch access to technology: A comprehensive guide by David Colven and Simon Judge is an excellent overview of the issues around using switches to control computers and other devices.
The main subject of this freely downloadable pdf document is the switch user. The document aims to encourage developers to include switch access into their products, and standardise practice and terminology. It explains some of the issues involved for people with severe physical difficulties who access computers and other electronic devices with switches. It details the ways in which switch users interact with computer programs and other technology designed to be directly accessible to them. It also attempts to survey the whole range of issues associated with switch use.