Asymmetric Digital Subscriber Line. This is a technology for delivering a high bit rate link to customers over ordinary copper. Data rates can reach 8mbps from the exchange to the customer and 640kbps in the other direction.

A serial data transmission method in which each character is transmitted as a self contained unit. Transmission is controlled by start and stop elements at the beginning and end of each character. Also called Star-Stop transmission.

Asynchronous Transfer Mode - A transfer mode in which the information is organised into cells. It is asynchronous in the sense that the recurrence of cells containing information from an individual user is not necessarily periodic.