A Dictionary of Common Computer Terms Access time The amount of time required to access data. Smaller the number,(usually expressed in milliseconds) the faster data can be read or written to/from the disk. See Msec. Application A program or a group of application programs that perform a set of tasks. While applications are programs not all programs are applications. An accounting ap- plication does accounts receivable, accounts payable, general ledger. Aspect ratio The shape of an object as measured by the ratio of the horizontal to the vertical dimensions. Usually refers the shape of a video or movie screen. When applied to pixels, it refers the square or rounded shape of each individual pixel. Asynchronous A method of transferring information without the source and destination being synchronized with one another. AT A PC based on Intel's 80286 processor chip. See XT. Autoexec The first file executed by the computer by DOS when the system is booted (started up via the boot switch or by pressing the Control Alt and Del keys) This file defines the initial settings (environment) of the computer. Auto-answering The ability of a modem to answer a ringing phone line without human intervention. (An expected feature of any modem) Auto-dialing The ability of a modem to send tones or pulses down the phone line as if a telephone had been dialed. This allows the modem to make a connection under computer control. Bandwidth The range of frequencies or the amount of information that can be passed through a channel within a specified time. Battery Backup A battery-based power source. 1. Generally used for keeping the computer's system configuration current in EPROM memory, (ie, date and time) even if the computer is powered down 2. Provides emergency power so a computer can be shut down gracefully if there is an interruption in the building's power. A term that is associated with a UPS system. See UPS. Baud The rate at which the carrier in digital communications system changes its state to convey information, allowing the actual information throughput in bits per second to be faster than the baud rate. Beta Test A testing period for hardware and/or software to verify correct operation. BIOS Basic Input Output System. The heart of the computer. Bit The smallest storage unit of information. Information is either a "1" or a "0". Eight bits equals one Byte. Bitmap A graphics term referring to the method in which a display is stored. See Raster, Vector. Bottom-Up A programming design technique by which the lowest level program task is written first then the next highest etc. as single program modules until the top level program is written. Also known as modular programming. Bus The common path between the CPU, memory, and device controllers. See ISA, MCA. Byte The smallest addressable unit of data. Comprised of 8 bits and can store one character (a letter, number or symbol). Cache A high speed memory, capable of storing a portion of a program allowing it operate faster than if the program was stored in main memory. CGA Color Graphics Adapter. Resolution xxx X xxx pixels (low resolution 16 colors). Obsolete, not used very often now. Campus A network term. A collection of sites in a compact area, such an office complex, college campus. Clone A PC other than one made by IBM, using an Intel 80xxx family of processor chips. In recent years other chip vendors have made processor chips. Color depth The maximum number of colors that a video board can display simultaneously. For example, a VGA card can display as many as 256 colors at a time. An EGA card can display 16 colors at a time. See Palette. Command line A command from the prompt to tell the computer which program to run. COMn Serial communication port. The computer be configured for a maximum of 4 ports (COM1, COM2, COM3, COM4). These ports are used for all communication (modems), some printers and sometimes for mouse control. See LPT. Configuration The hardware and software components that make up the system. Config.sys The file that tells a DOS how to configure memory and what device drivers to load. This program runs only at the time the system booted (started). Read by the auto- exec.bat file. Conventional Memory Main memory of the computer address range from 0 to 640 Kb. Data Information. It can be a bit, byte, word, database, etc. or report. Database A group of records. Also see Flat, or Relational database. Data Compression A means of packing information into fewer bytes by reducing redundant data. Data compression is partic- larly useful for modems by allowing for quicker trans- fers of data. Also useful for backing up data and the storing of graphic files. Many graphic file formats contain built-in compression routines. Data Rate The speed at which information bits can be transferred through a modem under the best possible conditions. For example, a Bell 212 A has a data rate of 1,200 bits per second. Density The number of an unit within a defined space. See DPI, LPM. Developer Writes applications for marketing or distribution. See Programmer. Device Driver A program that tells the operating system how to operate or drive a device. It can be a separate program with an extension of ".sys" ie. ANSI.SYS. Distributed System A system technique where computer applications are shared between a central computer and smaller computers (PCs) to allow for greater computer efficiency. See LAN, WAN. DPI Dots per inch (density). Higher the number, better the resolution. DOS Disk Operating System. Usually refers to MS/DOS, a proprietary operating system from Micro Soft used on most PCs. The most commonly versions are 3.3x and 5.0. Drive Short for disk or magtape drive. Duplex Modem communications that allow information to pass in both directions simultaneously. A duplex modem can send and receive over the same wiring. Also known as Full Duplex. EGA Enhanced Graphics Adapter. Resolution 640 x 350 pixels (medium to high with 64 colors). EISA Enhanced Industry Standard Architecture. An immature PC PC bus architecture. See ISA, MCA. End User An individual for whom programs or applications are intended. Also known as User. Environment An area of memory in which the operating system stores system-wide features. EPROM Erasable Programmable Read Only Memory. A hardware chip used to hold information regarding the system config- ration such date, time and disk type. Error Correction 1. A method of correcting the data in memory or disk. 2. A method of assuring data integrity of digital data transmissions including redundant information to ident- ify any changes that occur during a transmission. ESDI Enhanced Small Device Interface. Expanded memory The memory between 640 Kb and 1 Mb. First introduced in 1985 by Microsoft and Intel. Can address as much as 8 Mb without shifting processor mode. The Expanded Memory Manager (EMM) causes expanded memory to act like a file with a handle. Expansion Slot An internal slot that allows for the addition of more devices, ie. communications serial ports (modems), scanners. Extended memory The memory above the 1 Mb limit. Most systems today have more than 2 Mb of memory. Available on 80286 and above based systems. Field The smallest editable piece of information within a record, ie. the lastname in a personnel file. File A collection of data records. For example personnel names, salaries and hire dates. Flat database A collection of records that are not related to any other database. Floppy disk Typically a flexible disk that can removed from the disk drive. Capacity can range from 360 Kb to 1.44 Mb. Also known as diskette. Form Fixed screen format used for data input. Typically a copy of previously used paper form. See Template. Format 1. A specialized program that prepares the disk for use for the first time. Caution must be exercised or the system disk data could be lost. See Utility. 2. A method of inputting data from a template on the video screen. Formatted capacity The amount of usable space on a disk drive or magtape after the format utility has been ran. The capacity is usually stated in Mb on disks and magtapes, in Kb on older floppy disk drives. Some disks have capacities in the Gb (gigabyte) range. Front end The hardware and software used to preprocess data prior to sending it to a mini or main frame computer for further processing, useful in networks. Gb Gigabyte. A unit of measurement used on newer disk drives to state capacity. Graphics Symbols other than alphanumeric. Used to draw pictures, symbols on the video screen and printed forms. GUI Graphical User Interface. A graphics based program that is started from the operating system to control programs by ICONS rather than from the command line. Can be used used with or without a mouse (point and shoot). Windows is a example of a GUI. Half-duplex Modem communications allowing information to be trans- ferred in one direction at a time. See Duplex. Hard disk Typically a non-removable disk of high capacity. The capacity is normally stated in Mb. Hardware The hardware that comprises the system, disk, cpu, memory, monitor, etc. Hayes Command Set The de facto standard in the PC modem industry for commands that control the functions of a modem. Also called the AT command set (AT=ATtention). ICON A picture in the window environment that represents the command line to start a program. Interface 1. Hardware controller that plugs into the computer buss that allows the cpu to "talk" a device (ie disk drive.) Also allows the device to "talk" to the computer. See SCSI. 2. Software that allows the user to "talk" to the computer, also allows the computer to"talk" to user. See Application, GUI, Program, Windows Interlace A technique that displays a screen by alternately show- ing all of the even lines then all of the odd lines. Video formats that use interlacing can cause some money- tors to flicker ("SNOW") ISA Industry Standard Architecture. A bus standard for PCs. The de facto standard for PCs. See EISA, MCA. ISDN Integrated Services Digital Network is the telephone system of tomorrow that directly accepts digital signals. Kb Kilobyte. Unit of measurement used for memory and transfer rate. One Kb equals 1024 bytes (characters of information) LAPB An acronym for Link Access Procedure, Balance. An error control method used by X.25 packet-switching systems and some advanced modems. LAPM An acronym for Link Access Procedure for Modems. An error control method used by V.42 modems. LAN Local Area Network. A privately owned data commun- ications system that offers high-speed communications channels optimized for connecting information processing equipment (PCs, workstations and mainframe computers). Geographical area is usually limited to a building or a group of buildings. LIM Lotus Intel Microsoft memory management system for expanded memory (can be a combination of hardware and software). LPM Lines per minute. A unit of throughput (measurement) for line printers. Also see PPM. LPTn A parallel printer port. A computer can be configured for a maximum of 3 parallel printer ports (LPT1, LPT2, LPT3). See COM. Local The node (system) that you are physically on. Sometimes a group of nodes (systems) physically connected together via wiring. See LAN, Network. Locked record A method that allows only person to access and update a record at a time. This insures data integrity. Normally used in networked environments. Log A file used to record usage and updates on a system or network. Mb Megabyte a unit of measurement used for memory and storage devices ie. disks, magtapes. MCA Micro Channel Architecture. An IBM proprietary 32 bit bus architecture. Limited products are supported. See ISA, EISA. MDA Monochrome Display Adapter. A one color display on a black background, usually green on black or white on black. Memory management A system to control memory, can be a combination of hardware and software. See LIM, extended memory and expanded memory for further definition. Menu A programming technique that allows the user to use a key word to start or control a program or system without remembering complex command strings to start a program. This technique is more "user friendly". There are commercially available programs that allow for custom setups. Megahertz One million cycles (hertz) per second. Most commonly associated with cpu speed, higher the number the faster the cpu can process data. See Microsecond. Metafile A class of graphics file formats that can accommodate both raster and vector information. See Raster, Vector. Microsecond Microsecond. One one-millionth of a second. Abbreviated us. Most commonly associated with cpu speed. Higher the number, the faster the cpu will operate. See Mhz. Msec Millisecond. One one-thousandth of a second. Abbreviated MS, ms, Msec. Most commonly associated with disk access times, lower the number the quicker the disk can access data. MNP Microcom Networking Protocol is a set of standards for various aspects of the operation of modems including error correction, data compression, line optimization, and data rate negotiation. Modem MOdulator/DEModulator. A communication device that converts digital data from the computer to analog data from transmission on a telephone line and back again on the other end. Mouse A pointing device used to point to items in a menu, rather than typing on a keyboard. Also a must for graphic drawing programs ie. CAD (Computer Aided Drafting). The mouse usually has a SERIAL interface, however, the mouse could be parallel or a buss type. See GUI, Point and shoot, Windows. Nanosecond Nanosecond. One one-billionth of a second. Abbreviated Ns. Most commonly associated with the internal memory chip speed. Lower the number, the faster the memory. Network A group of computers connected by wiring. Devices such as printers and data files can be shared, thus reducing capital equipment expenditures and system overhead. Distributed systems, LANs and WANs are examples of networks. Node A single data entry point (mainframe, terminal or PC) on a network. See Distributed system, LAN, Network or WAN. Operating System The control program to provide services such as scheduling, timing, memory management, etc. from which all other programs are started from. Palette The total number of colors that a video card can use. Typically, a board can display only a portion of its palette at a time. An VGA card can display 256 colors from a palette of 262,144 colors. An EGA card can dis- play 16 colors from a palette of 64 colors. A CGA can display 16 colors. See color depth. Password A method of controlling access to a system, particular applications or files. Identifies the individual users. Passwords must be guarded or the system information will be compromised which could cause a major loss of data or business if the information landed in the wrong hands. Pitch 1. The size of pixel when describing the resolution of a monitor. Smaller the number better the resolution. 2. The number of characters per inch. Higher the number, smaller the letters. Pixel A single point on a monitor or laser printer page. Measured in thousandths of a inch. Smaller the number the higher the resolution, ie. .28 of an inch. See CGA, EGA, VGA. Point and Shoot A term used with mouse devices. A method of pointing to an item on a menu or from a window and clicking a button (shooting) rather than typing the command on the key board. See GUI, Mouse, Windows. PPM Pages per minutes. A unit of measurement used with line printers and laser printers. Process A logical way to analyze, control the computer. Can be a program or application. Program A set of instructions that enables the computer to solve a problem. Programmer An individual who writes programs. Prompt A character(s) that prompts the user that the computer is ready to accept a command. RAM Random Access Memory. The memory that computer uses for programs and data. The contents are lost when the computer loses power or is turned off. Raster 1. The scanning of a monitor horizontally from left to to right at a specific frequency. 2. A method of coding and storing a graphics image as a pattern of dots. See Bitmap Record A collection of fields that pertain to a particular piece of information. For example the Name, hire date, salary, commission for an individual. See Field, Data base. Relational database A group of databases that are related, ie. Salesmen, Payroll (Personnel), Inventory, Account Receivables by a single link (most of the time) from each database. See Flat database. Remote A system other than the one you are actually on. See LAN, Network, Modem. Resolution The number of pixels or dots per inch. Higher the number better the resolution. See EGA, Pixel, VGA. ROM Read Only Memory. A type of memory whose contents are permanently recorded and is not lost when the computer has lost power or is turned off. Measured in Kb or Mb. SCSI Small Computer System Interface. Allows for up to 7 devices on the same device controller. Shared devices A device on a network than reduces redundant equipment purchases. For example two laser printers shared between 10 users. Shared file A file on a database server in a network environment. See LAN, Network, WAN Shareware A software distribution method that allows for " try before you buy". A cost effective way to purchase soft- ware for a particular application. Shell An executive program that monitors, controls other programs and hardware. See Operating System. Software A group of computer instructions that tell the computer what to do. Also known as programs. Can also be a group of programs that can perform many functions such as accounting. See Interface. SQL Structured Query Language. A data definition and data manipulation language for relational databases. SVGA Super Video Graphics Adapter. Resolution 1024 x 768 pixels. System A combination of hardware and software to perform a function. Table A database used with SQL. Template A "fill in the blanks" form used in word-processing. Text The alphanumeric symbols that displayed on the screen or are printed, ie. word-processing. Top-Down A programming term to describe a method of designing an application, starting with the highest level of an ap- plication. Top Down design breaks an application into many specific tasks. The breakdown is hierarchical, with higher tasks activating lower level tasks. See Bottom-Up. TSR Terminate and Stay Resident in memory. Too many TSRs in memory can adversely affect the operation of the system and some programs may not run until some or all TSRs have been removed from memory. Tuple A database term that relates to a ROW within a table. UPS Uninterruptable Power Source/Supply. 1. These are generally used were utility power is subject to "brown outs", power outages, etc. 2. Critical computer applications. uS See Microsecond. Utility A special program to perform a special function (s), ie. format, diagnostics. Vector 1. A graphics term to describe a coding and storage technique a graphics image as straight lines. See Bitmap, Raster. Version A alphanumeric method of tracking revisions of hardware and software. VGA Video Graphics Adapter. Resolution 640 x 480 pixels. Virus A destructive program designed to destroy data on a computer. Can also be a time bomb. Not all programs with a limited life span (program will self destruct without damaging any other files. MOST legitimate programs and applications state this up front!) are viruses. It is best to steer clear of any programs that will self destruct. Always read the documentation on a new program/application prior to using! There are many virus protection utilities around. There is not a single utility that will protect against ALL viruses! Prudence is the best policy when adding new /copies of programs from friends and Bulletin Boards (BBSes). WAN Wide Area Network. A WAN can have many nodes on both coasts. See LAN, Network, Node. Watt A unit of electrical power derived from Ohm's Law. Used to describe how much power is generated or consumed by a device, ie. the typical pc power supply is rated at 230 watts. The typical pc monitor consumes 40 watts per hour. Watt=Volts x Amperes (for DC power) Windows A software program that allows you to have more than one meaningful screen on the monitor at a time. See GUI. Word 1. Two bytes of data. 2. Text in a word processing file. XT A PC based on Intel's 8086 processor chip. See AT. Acknowledgments MS-DOS Registered trademark of Microsoft Corporation. Windows Registered trademark of Microsoft Corporation. IBM Registered trademark of International Business Machines. dBase Registered trademark of Ashton-Tate.