Binary Representation:
Pertaining to the presence or absence of electronic or magnetic "signals" in the computer’s circuitry or in the media it uses. There are only two possible states or conditions - presence or absence.

Central Processing Unit (CPU):
The unit of a computer system that includes the circuits that controls the interpretation and execution of instructions. In many computer systems, the CPU includes the arithmetic-logic unit, the control unit, and primary storage unit.

Computer System:
Computer hardware as a system of input, processing, output, storage, and control components. Thus a computer system consists of input and output devices, primary and secondary storage devices, the central processing unit, the control unit within the CPU, and other peripheral devices.

Computer Terminal:
Any input/output device connected by telecommunications links to a computer.

Digital Cameras:
Digital still cameras and digital video cameras enable you to shoot, store, and download still photos or full-motion video with audio in your PC.

Direct Access:
A method of storage where each storage position has a unique address and can be individually accessed in approximately the same period of time without having to search through other storage positions.

Downsizing:
Downsizing computer platforms results from using networks of microcomputers to replace minicomputers and mainframes.

Generations of Computing:
Reflect stages in the development of electronic computers, characterized by major changes in technology or performance.

Information Appliance:
Devices for consumers to access the Internet.

Laptop Computer:
A small portable PC.

Liquid Crystal Displays (LCD):
Electronic visual displays that form characters by applying an electrical charge to selected silicon crystals.

Magnetic Disk Storage:
Data storage technology that uses magnetized spots on metal or plastic disks.

Magnetic Disk Storage - Floppy Disk:
Small phonograph record enclosed in a protective envelope. It is a widely used form of magnetic disk media that provides a direct access storage capability for microcomputer systems.

Magnetic Disk Storage - Hard Disk
Secondary storage medium; generally nonremovable disks made out of metal and covered with a magnetic recording surface. It holds data in the form of magnetized spots.

Magnetic Disk Storage - RAID
Redundant array of independent disks. Magnetic disk units that house many interconnected microcomputer hard disk drives, thus providing large, fault tolerant storage capacities.

Magnetic Ink Character Recognition (MICR):
The machine recognition of characters printed with magnetic ink. Primarily used for check processing by the banking industry.

Magnetic Tape:
A plastic tape with a magnetic surface on which data can be stored by selective magnetization of portions of the surface.

Magnetic Stripe:
A magnetic stripe card is a plastic wallet-size card with a strip of magnetic tape on one surface; widely used for credit/debit cards.

Mainframe Computer:
A larger-size computer system, typically with a separate central processing unit, as distinguished from microcomputer and minicomputer systems.

Microcomputer:
A very small computer, ranging in size from a "Computer on a chip" to a small typewriter-size unit.

Microprocessor:
A semiconductor chip with circuitry for processing data.

Midrange Computer:
Larger and more powerful than most microcomputers but are smaller and less powerful than most large mainframe computer systems.

Minicomputer:
A small electronic general-purpose computer.

Network Computer:
A new category of microcomputer designed mainly for use with the Internet and Intranets on tasks requiring limited or specialized applications and no or minimal disk storage.

NetPC
Low-cost networked-enabled PCs with reduced features.

Network Server:
A type of midrange computer used to co-ordinate telecommunications and resource sharing and manages large web sites, Intranets, extranets, and client/server networks.

Network Terminal:
A terminal that depends on network servers for its software and processing power.

Off-line:
Pertaining to equipment or devices not under control of the central processing unit.

Online:
Pertaining to equipment or devices under control of the central processing unit.

Optical Character Recognition (OCR):
The machine identification of printed characters through the use of light-sensitive devices.

Optical Disk Storage:
Technology based on using a laser to read tiny spots on a plastic disk. The disks are currently capable of storing billions of characters of information.

Optical Disk Storage - CD-ROM:
An optical disk technology for microcomputers featuring compact disks with a storage capacity of over 500 megabytes.

Optical Disk Storage - CD-R:
Compact disk recordable (CD-R) enables computers with CD-R disk drive units to record their own data once on a CD, than be able to read the data indefinitely.

Optical Disk Storage - CD-RW:
Compact disk rewritable (CD-RW) enables computers with CD-RW disk drive units to record and erase data by using a laser to heat a microscopic point on the disk’s surface.

Optical Disk Storage - DVD:
Digital video disk or digital versatile disk (DVD) enables computers with DVD disk drive units to hold from 3.0 to 8.5 gigabytes of multimedia data on each side of a compact disk.

Optical Disk Storage - WORM Disk:
Optical disk that allows users to write once, read many times.

Optical Scanning:
Using a device (scanner) that scans characters or images and generates their digital representations.

Pen-Based Computing:
Tablet-style microcomputers that recognize hand-writing and hand-drawing done by a pen-shaped device on their pressure sensitive display screens.

Peripheral Devices:
In a computer system, any unit of equipment, distinct from the central processing unit, that provides the system with input, output, or storage capabilities.

Personal Digital Assistant:
Handheld microcomputer devices which are designed for convenient mobile communications and computing.

Pointing Devices:
Devices, which allow end users to issue commands or make choices by moving a cursor on the display, screen.

Pointing Device - Electronic Mouse:
A small device that is electronically connected to a computer and is moved by hand on a flat surface in order to move the cursor on a video screen in the same direction. Buttons on the mouse allow users to issue commands and make responses or selections.

Pointing Device - Pointing Stick:
A small buttonlike device sometimes likened to the eraser head of a pencil. The cursor moves in the direction of the pressure you place on the track point.

Pointing Device - Touchpad:
Is a small rectangular touch-sensitive surface usually placed below the keyboard. The cursor moves in the direction your finger moves on the pad.

Pointing Device - Trackball:
A roller device set in a case used to move the cursor on a computer’s display screen.

Primary Storage:
The main (or internal) memory of a computer. Usually in the form of semiconductor storage.

Printers:
Devices that produce hard copy output such as paper documents or reports.

Secondary Storage:
External or auxiliary storage device that supplements the primary storage of a computer.

Semiconductor Memory:
Microelectronic storage circuitry etched on tiny chips of silicon or other semiconducting material.

Semiconductor Memory - RAM:
Also known as main memory or primary storage; type of memory that temporarily holds data and instructions needed shortly by the CPU. RAM is a volatile type of storage.

Semiconductor Memory - ROM:
Also known as firmware; a memory chip that permanently stores instructions and data that are programmed during the chip’s manufacture. Three variations on the ROM chip are PROM, EPROM, and EEPROM. ROM is a non-volatile form of storage.

Sequential Access:
A sequential method of storing and retrieving data from a file.

Smart Cards:
Cards such as debit and credit cards, which have an embedded microprocessor chip and several kilobytes of memory.

Speech Recognition:
Direct conversion of spoken data into electronic form suitable for entry into a computer system. Promises to be the easiest, most natural way to communicate with computers.

Storage Capacity Elements:
Units used for storage capacity and data: bits, bytes, kilobytes (KB), megabytes (MB), gigabytes (GB), terabytes (TB).

Storage Capacity Elements - Bit:
A contraction of "binary digit". It can have the value of either 0 or 1.

Storage Capacity Elements - Byte:
A sequence of adjacent binary digits operated on as a unit and usually shorter than a computer word. In many computer systems, a byte is a grouping of eight bits that can represent one alphabetic or special character or can be "packed" with two decimal digits.

Storage Capacity Elements - Kilobyte (K or KB):
When referring to computer storage capacity it is equivalent to 2 to the 10th power, or 1,014 in decimal notation.

Storage Capacity Elements - Megabyte (MB):
One million bytes. More accurately, 2 to the 20th power, 1,048,576 in decimal notation.

Storage Capacity Elements - Gigabyte (GB):
One billion bytes. More accurately, 2 to the 30th power, or 1,073,741,824 in decimal notation.

Storage Capacity Elements - Terabyte (TB):
One trillion bytes. More accurately, 2 to the 40th power, or 1,009,511,627,776 in decimal notation.

Storage Media Trade-offs:
The trade-offs in cost, speed, and capacity of various storage media.

Supercomputer:
A special category of large computer systems that are the most powerful available. They are designed to solve massive computational problems.

Time Elements:
Units used for measuring processing speeds: milliseconds, microseconds, nanoseconds, and picoseconds.

Time Elements - Millisecond:
A thousandth of a second.

Time Elements - Microsecond:
A millionth of a second.

Time Elements - Nanosecond:
One billionth of a second.

Time Elements - Picosecond:
One trillionth of a second.

Touch-Sensitive Screen:
An input device that accepts data input by the placement of a finger on or close to the CRT screen.

Trends in Computers:
Smaller, faster, and cheaper.

Video Output:
Video displays are the most common type of computer output.

Volatility:
Memory (such as electronic semiconductor memory) that loses its contents when electrical power is interrupted.

Wand:
A handheld optical character recognition device used for data entry by many transaction terminals.

Workstation:
A computer terminal or micro- or minicomputer system designed to support the work of one person. Also, a high-powered computer to support the work of professionals in engineering, science, and other areas that require extensive computing power and graphics capabilities.