The Alt key on a computer keyboard gives alternate meanings to other keys, thus expanding the keyboard's capability. The Alt key is held down like a Shift key, and another key is pressed.

Auto Answer. Some modems can be set up to accept telephone calls and automatically establish a connection; this ability is called auto answer. When the AA light on the modem goes on, the modem is set to auto answer.

Average Access Time. The average amount of time it takes for a storage peripheral to transfer data to the CPU.

Advanced Basic Input/Output System. A BIOS that is compatible with the latest software and peripherals.

Automatic Built-In Self-Test. An automatic self-test performed by an IBM computer to make sure its various components are functioning properly.

(Automatic Baud Rate detection). The process in which a receiving device examines the first character of an incoming message to determines its speed, code level, and stop bits. Having this automatic function makes it possible to receive data from different transmitting devices operating at different speeds without having to establish data rates in advance.

Asynchronous Communications Device Interface. A software device that permits asynchronous transmission, a way of transmitting data in which one character is sent at a time, and there may be uneven amounts of time between characters. A start bit and a stop bit notify the receiving computer when the transmission begins and ends. In synchronous transmission, strings of multiple characters are transmitted; this method is faster, but more expensive.

Abbreviation for ACKnowledge. A modem receiving a data packet sends a signal back to the modem that sent it. If the data is complete and correct, it sends an ACK (acknowledgement) signal, which also indicates the next data packet should be sent. If the modem didn't get all the data, it sends back a NAK, or negative acknowledgement signal.

Advanced Communications Services.

A service offered by Infonex, Inc. that allows user to surf the Web anonymously. www.anonymizer.com.