We dedicate this book to John Southall.
John was a member of the BCS staff and Registrar. He was instrumental in forming the Working Party of BCS Schools Committee members in the 1970s that started the small Glossary, which evolved over the years into the current edition. John’s wit, wide knowledge of computer terminology and of BCS, and his attention to detail, made him a strong support for those who follow on. He was working on this thirteenth edition when he died.