IBM XT 5160 Technical Reference page 374

assembler language. A computer-oriented language whose
instructions are usually in one-to-one correspondence with
computer instructions.
asynchronous transmission. ( 1) Transmission in which the time
of occurrence of the start of each character, or block of
characters, is arbitrary; once started, the time of occurrence of
each signal representing a bit within a character, or block, has the
same relationship to significant instants of a fixed time frame.
(2) Transmission in which each information character is
individually transmitted (usually timed by the use of start
elements and stop elements).
audio frequencies. Frequencies that can be heard by the human
ear (approximately 15 hertz to 20,000 hertz).
auxiliary storage. (1) A storage device that is not main storage.
(2) Data storage other than main storage; for example, storage
on magnetic disk. (3) Contrast with main storage.
BASIC. Beginner's all-purpose symbolic instruction code.
basic input/output system (BIOS). The feature of the IBM
Personal Computer that provides the level control of the major
110 devices, and relieves the programmer from concern about
hardware device characteristics.
baud. (1) A unit of signaling speed equal to the number of
discrete conditions or signal events per second. For example, one
baud equals one bit per second in a train of binary signals,
one-half dot cycle per second in Morse code, and one 3-bit value
per second in a train of signals each of which can assume one of
eight different states. (2) In asynchronous transmission, the unit
of modulation rate corresponding to one unit of interval per
second; that is, if the duration of the unit interval is 20
milliseconds, the modulation rate is 50 baud.
BCC. Block-check character.
beginner's all-purpose symbolic instruction code (BASIC). A
programming language with a small repertoire of commands and a
simple syntax, primarily designed for numeric applications.
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