Glossary of terms - PC Based Instrumentation and Control - page 446

AND Logical function which is asserted (true) when all inputs are simultan-
eously asserted.

ANSI character set The American National Standard Institute's (ANSI) char-
acter set which is based on an 8-bit binary code and which provides 256
individual characters. See also ASCII .

Archive A device or medium used for storage of data which need not be
instantly accessible (e.g. a tape cartridge).

ASCII A code which is almost universally employed for exchanging data
between microcomputers. Standard ASCII is based on a 7-bit binary code and
caters for alphanumeric characters (both upper and lower case), punctuation,
and special control characters. Extended ASCII employs an 8th bit to provide
an additional 128 characters (often used to represent graphic symbols).

Assembly language A low-level programming language which is based on
mnemonic instructions. Assembly language is often unique to a particular
microprocessor or microprocessor family.

Asserted A term used to describe a signal when it is in its logically true state
(i.e. logic 1 in the case of an active high signal or logic 0 in the case of an active
low signal).

Asynchronous transmission A data transmission method in which the time
between transmitted characters is arbitrary. Transmission is controlled by start
and stop bits (no additional synchronizing or timing information is required).

ATAPI The ATAPI (or Advanced Technology Attachment Packet Interface)
standard provides a simple means of connecting a CD-ROM drive to an EIDE
adapter. Without such an interface, a CD-ROM drive will require either a
dedicated interface card or an interface provided on a sound card.

AUTOEXEC.BAT A file which contains a set of DOS commands and/or pro-
gram names which is executed automatically whenever the system is initialized
and provides the means of configuring a system.

Backup A file or disk copy made in order to avoid the accidental loss, damage,
or erasure of programs and/or data.

Basic Input Output System (BIOS) The BIOS is the part of the operat-
ing system which handles communications between the microcomputer and
peripheral devices (such as keyboard, serial port, etc.). The BIOS is supplied
as firmware and is contained in a read-only memory (ROM).

Batch file A file containing a series of DOS commands which are executed
when the file name is entered after the DOS prompt. Batch files are given a
BAT file extension. A special type of batch file (AUTOEXEC.BAT) is executed
(when present) whenever a system is initialized. See also AUTOEXEC.BAT .

Baud rate The speed at which serial data is transferred between devices.

Binary file A file which contains binary data (i.e. a direct memory image).
This type of file is used for machine readable code, program overlays, and
graphics screens.