Glossary: Chapter 4

analog/digital input: Hardware that senses a physical measurement, like the directional movement of a mouse, and converts it to digital data for input to the computer.
arithmetic/logic unit: The processor unit in the CPU that performs arithmetic and comparison operations.
ASCII (American Standard Code for Information Interchange): The most common character code used for microcomputers and data communications. Standard ASCII consists of seven bits per character; Extended ASCII of eight bits.
automated teller machine (ATM): An interactive input/output device for banking where customers gain access to the machine by means of a PIN (personal identification number). Normally they can then make deposits, withdraw money, and get other information about their accounts.
binary integer: A whole number, either positive or negative, composed of binary digits 0 and 1 representing powers of 2.
bit-mapped: A term used to describe images composed of patterns of dots and displayed on graphics computer screens.
bit: An abbreviation for binary digit, which can be either 0 or 1.
byte: A unit of memory in the computer consisting of eight consecutive bits, often used to store one character of data or information.
cathode ray tube (CRT) or visual display terminal (VDT): The most common type of computer screen or monitor.
CD-ROM: A compact disk on which large volumes of information are stored digitally and accessed by laser beam.
central processing unit (CPU): The core of a microcomputer system. It contains both the arithmetic/logic unit and the control unit.
core memory: An older kind of random-access memory (RAM) device that held its magnetic charge even when the power was off. RAM memory chips replaced core memory because core was more expensive to produce, larger in size, and slower to access.
cursor: A small blinking arrow, vertical line, or underline on a computer screen to indicate where the next input will be displayed.
digital (numeric) data: A term that applies to forms of data that can be expressed in numeric terms, and thus can be readily processed by digital computers.
disk drive: The most common form of secondary storage hardware device. A drive can read programs and data stored on diskettes or hard disks and transfer them to internal memory.
diskette: The most common form of secondary storage -- small, inexpensive, and portable -- which records data as magnetized bits that are read by a disk drive.
EBCDIC (Extended Binary Coded Decimal Interchange Code): A standard character code using 8 bits per character devised for IBM mainframes in the 1960s but less frequently used today than ASCII.
flatbed scanner: An input device to digitize photographs and drawings as a set of dots, called pixels, so that they can be processed by computers.
gigabyte (GB): A measure of main memory or auxiliary storage size, comprising one billion storage positions.
graphical user interface (GUI): A computer interface, commonly accessed with a pointing device like a mouse, that uses pictures, graphic symbols, windows, and menus to represent commands, choices, and actions.
hard copy: Output printed on paper.
ink-jet printer: An inexpensive nonimpact printer in which tiny dot patterns are sprayed onto paper to form characters.
integer: Any positive or negative whole number, including zero.
kilobyte (KB): A unit of storage equal to 1024 bytes of main or auxiliary memory.
kilohertz (kHz): A measuring unit for a sound wave, representing a thousand cycles per second.
laser printer: A popular nonimpact printer that creates high-quality output by using a laser beam to create an image on an electrically charged drum.
magnetic ink character recognition (MICR): An input process used by banks to read the digits and symbols printed in magnetic ink at the bottom of checks.
Magneto-optical (MO): Mass storage that combines magnetic and laser technology for safe, portable storage of massive amounts of information in gigabyte quantities.
matrix: An arrangement of data in a grid of rows and columns suitable for storing the pixel layout of a bit-mapped character or graphic in computer memory.
memory: The functional component of a computer that stores programs and data before they are processed by the CPU.
menu: A list of choices displayed on the screen from which a user can select program operations. A computer with a GUI often presents menus in pull-down form.
MIPS (million instructions per second): One measure of a computer's processing speed, sometimes used to compare how many instructions different microprocessors can execute in a second.
monochrome screen: A computer screen offering one color, typically white, green, or amber, against a black background.
motherboard: The main circuit board of a computer containing the microprocessor, memory chips, and other components.
nanosecond: A billionth of a second, the unit of magnitude that personal computer internal speeds are measured in today.
near letter quality (NLQ): Fine-quality printing produced by dot-matrix printers in their best resolution, which is almost as good as that produced by fully formed characters.
numeric character: A number stored as ASCII codes inside a computer, rather than being stored as a binary integer or floating-point real number. A street number or zip code as part of an address is an example.
optical character recognition (OCR): An input process that scans a printed character in a book or reads a number on a check and translates them into computer-readable codes.
place system: The basis of any number system, such as decimal or binary integers. A digit in a certain place means that the digit is raised to the power of the base number for that place. For instance, the 2 in the "tens" place in the number 20 must be multiplied by 10 to get its value.
plotter: An output device that creates a graphic image by controlling the motion of a pen on paper.
primary storage: The functional component of a computer where programs and data are stored for processing, normally RAM in PCs.
read-only memory (ROM): Memory chip that permanently stores instructions and data. Because it can be read from but cannot have new information put into it, manufacturers store important control programs in ROM chips.
real number: A positive or negative number, including zero, that can be expressed with fractions, called floating point in computers because they are represented with a floating binary point similar to a decimal point.
resolution: A term referring to the number of pixels on a computer screen. The higher the resolution, the better the characters or images on the screen appear.
RGB (red-green-blue) monitor: A term for a color monitor, with the letters of the name standing for the three primary additive colors that combine to make color images on the screen.
secondary mass storage: A term that applies to the medium in which computer programs and data are stored while not in use, such as on diskettes or magnetic tape.
semiconductor memory: Another term for RAM chips, based on a semiconductor technology similar to that of microprocessor chips.
slide scanner: An input device for digitizing color slides directly so that they are suitable for storage in computers.
soft copy: Computer output presented on a CRT screen rather than being printed.
synthesizer: A device that can electronically generate sound, either music or voice, from digital information.
touch screen: An input/output device that allows a user to control the computer by touching the screen, which then displays the output.
Unicode: A new standard coding scheme that allows 65,536 different binary codes because it uses 16 bits to code a character.
voiceprint: An audio signature of a person in digital form, useful for allowing a computer system to recognize a person's voice commands.
window: A resizable rectangular display area of a computer screen, prominent in systems having a graphical user interface.

Glossary: Chapter 4

[Chapter Contents] [Home] [Glossary]