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Resources - Glossary (D, E, and F)

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D

daisy chain
A method of connecting a series of
peripherals on a bus in a chain. A signal is sent from the CPU along this chain of devices, if the device did not request the signal it passes it along to the next device.

DAT - digital audio tape.
An audio tape similar to a magnetic cassette tape but using a
digital process of recording and playing back.

database
A series of files connected and related by data objects it contains. In database programs, a database may contain forms, tables, queries, and other data manipulation files.

decompression
The process of taking a
compressed file and returning it to its original uncompressed state.

decryption
The process of de-coding an
encrypted set of data using the code's key.

dedicated line
A communication line, often a telephone or
ISDN line, that provides a specific function such as a modem connecting line.

delimiter
An item that divides data fields. Commonly used delimiters include a comma, space, or tab character.

desktop
The windows, icons, dialog boxes,
aliases, and other items that appear on the computer screen of Macintosh®es and Microsoft® Windows®-based PCs.

desktop computer
A computer that resides on the desk's top; a desktop computer is non-portable and can not function as a mainframe computer.

device ID
An identifying
ASCII string used to identify each hardware device from another; i.e., an internal CD-ROM, a hard drive, a printer, etc., will each have their own unique device ID.

dialog box
A small window that appears on the
desktop typically either notifying the user of some event (e.g., a system error) and requesting input from the user ("OK" to print).

dial-up connection
A connection between two devices over the telephone lines; e.g., connecting to an email service provider.

digital
A system that defines data in a discrete, non-fluctuating (i.e., non-
analog), numerical method. Similar to a binary system.

digital audio tape - DAT.
An audio tape similar to a magnetic cassette tape but using a
digital process of recording and playing back.

digitalize
The process of converting a non-digital item (e.g., a photograph or VHS video clip) into a
digital data object.

digital video disk - DVD.
An optical storage medium that can store video, audio, and text. This medium is beginning to replace magnetic video tapes.

DIMM - dual inline memory module.
A pre-assembled
RAM module that contains many smaller memory chips. A DIMM has a 168-pin connector allowing for 64-bit data transfer, twice the data transfer rate of SIMMs (single inline memory module).

DIP switch - dual inline package switch.
A series of small switches on hard devices like
hard drives used to define the configuration of that piece of hardware. For example, on computers with 2 hard drives, the DIP switches are used to define which hard drive is the master (primary) and which is the slave (secondary) hard drive.

direction keys
Sometimes also called
arrow keys. The keys are usually found together on the key board and have an up, down, left, and right direction.

directory
A organizational technique used to store computer files. A directory can contain files,
applications, or other directories called sub-directories. On computers with graphical user interfaces (GUIs), directories are called folders.

directory path name
The complete name of the directory starting with the root directory (top level directory). A directory name may be for example, c:/documents/personal. (See also
absolute path name and path. Compare to relative path name.)

disk cache
Using the
hard drive as a memory cache for faster data retrieval. Disk cache is used as temporary higher-speed storage and transfer of data. Cache is used because it improves computer performance making it faster. Cache memory can also be dedicated fast RAM memory.

disk
A portable storage disk. Disks come in a variety of sizes and capacities. Older versions included the 5 1/4 x 5 1/4 inch floppies. Newer versions are the 3.5 inch disks with about 1.4
MB storage capacity. Even newer magneto-optical disks such as Zip disks, can store about 100 MB of storage, while Jazz disks can be as large as 2 GB.

disk drive
The part of the
hard drive that holds and spins the disk. The heads of the disk drive read and write data to the disk.

disk partition
Disk partition occurs when a segment of a disk is set aside for a specific system file or function. Disk partitioning can also refer to the process of dividing a
hard drive's disk into smaller segments for more efficient data storage.

dithering
Simulating an unavailable color usually on a monitor by using other colors. A common example of this is with the
world wide web; not all colors are available on all monitors and computer systems so those colors not available on the client computer are dithered to create a similar color as the one on the server.

DNS
1. domain name service. A service that takes a domain and searches until a specific host is found.
2. domain name server. A
server that provides routing for a particular domain (i.e., wisc.edu).
3. domain name system. A system that converts IP addresses into a specific domain.

domain/domain name
A name such as wisc.edu that identifies the host or organization with that name.

domain name service - DNS.
A
server that provides routing for a particular domain (i.e., wisc.edu).

domain name service - DNS.
A service that takes a domain and searches until a specific host is found.

domain name service - DNS.
A system that converts
IP addresses into a specific domain.

dots per inch - DPI.
A measure of the
resolution of a scanner, printer, image, etc. The higher the dots per inch, the higher the resolution.

download
The process of transferring data from one computer to another. Usually, download refers to the transfer of data from a
server to a client computer. The opposite of upload.

downtime
The time when a
desktop or network computer is down and unavailable to use.

DPI - dots per inch.
A measure of the
resolution of a scanner, printer, image, etc. The higher the DPI, the higher the resolution.

drag
The process of moving an object on a graphical user interface (
GUI) computer by holding the mouse button down while moving the mouse.

drag and drop
The process of dragging a
GUI item such as a document and then releasing the mouse button to copy, print, or perform some function on that data object.

DRAM - dynamic random access memory.
DRAM is a type of
RAM that contains a capacitor and requires refreshing since capacitors gradually lose their charge over time. Data transfer rates are slower with DRAM than with static RAM (SRAM), about 60 versus 10 nanoseconds, respectively.

driver/device driver
Software that is used to interface the computer's operating system with external hardware such as printers or scanners.

drop-down menu
A
menu that drops down when a user chooses a menu title in the menu bar.

dual inline memory module - DIMM.
A pre-assembled
RAM module that contains many smaller memory chips. A dual inline memory module has a 168-pin connector allowing for 64-bit data transfer, twice the data transfer rate of SIMMs (single inline memory module).

dual inline package switch - DIP switch.
A series of small switches on hard devices like
hard drives used to define the configuration of that piece of hardware. For example, on computers with 2 hard drives, the dual inline package switches are used to define which hard drive is the master (primary) and which is the slave (secondary) hard drive.

DVD - digital video disk.
An optical storage medium that can store video, audio, and text. This medium is beginning to replace magnetic video tapes.

dynamic random access memory
DRAM. Dynamic random access memory is a type of
RAM that contains a capacitor and requires refreshing since capacitors gradually lose their charge over time. Data transfer rates are slower with dynamic random access memory than with static RAM (SRAM), about 60 versus 10 nanoseconds, respectively.

E

EIDE - enhanced integrated device electronics.
A disk format used by most common
platforms in which the controller electronics reside within the drive housing removing the need for a separate adapter. Other formats include SCSI, UltraSCSI, and IDE.

em dash
A dash (-) the width of the letter M in the same font and font size.

emulator
The process where one computer mimics another computer; for example, a
Macintosh® computer emulating a Microsoft® Windows®-based computer. Once emulated, the computer theoretically has the same functioning capacities as the computer it is emulating.

encryption
The process of protecting a set of data usually for security reasons. The process codes the data which can later be de-coded (
decryption) using the code's key.

en dash
A dash (-) half as wide as the
em dash in the same font and font size.

Encapsulated PostScript® - EPS.
A graphical file format used with
desktop publishing programs.

end of file - EOF.
A marker on a file to designate the end of the file has been reached.

enhanced integrated device electronics - EIDE.
A disk format used by most common
platforms in which the controller electronics reside within the drive housing removing the need for a separate adapter. Other formats include SCSI, UltraSCSI, and IDE.

EOF - end of file.
A marker on a file to designate the end of the file has been reached.

EPS - Encapsulated PostScript®.
A graphical file format used with
desktop publishing programs.

Ethernet
A networking system that enables high speed data communication over coaxial cables. The Ethernet
network system supports TCP/IP, AppleTalk®, Novell Netware®, and other network protocols.

expansion bus
Control lines that interface with devices on the system board or
expansion cards. Common expansion buses include USB and PCI.

expanison card
A
processor that can be added to an expansion slot located on the motherboard of a PC. The card can be a video accelerator card (a processor dedicated to processing video) or it can function in a variety of other capacities. Also called a card.

expansion slot
The location on the
motherboard that the expansion card connects to.

extension
Typically a 3 letter ending that follows the file name and is separated by a period. Extensions are used in
MS-DOS systems and often used with world wide web pages' graphics and other multimedia files. Common extensions include .doc, .wpd, .txt., .rtf for word processing documents; .gif, .jpg., .bmp, .psd, .png, and many more for image files; .wav and .aiff for audio files; and .mov, .mpeg, .avi for video files.

F

FAQ - frequently asked questions.
A document that tries to answer frequently asked questions. This is a popular mode of support with the
world wide web.

FAT - file allocation table.
1. A table used by an
operating system to keep track of the files stored on the hard drive disk. Often files are broken into segments on a hard drive disk with each segment being record by FAT and associated with that file. The FAT is used when the file is open or run so the various segments can be sequenced together.
2. An application that is compiled to run on 2 platforms. For instance, on Macintosh® computers, a FAT application could run on a PowerPC or a 680x0 platform.

fiber-optic cable
A data transmission wire made of glass or plastic. Data is transmitted using a modulated laser pulse.

FIFO - first in/first out.
A method of processing the first file in the order it was sent. Typically used with printer queues.

file
A block of stored information that can be retrieve with a computer.

file allocation table - FAT.
A table used by an
operating system to keep track of the files stored on the hard drive disk. Often files are broken into segments on a hard drive disk with each segment being record by FAT and associated with that file. The FAT is used when the file is open or run so the various segments can be sequenced together.

file format
The file structure that determines how the file is organized and displayed on a monitor, printer, etc.

File Manager
The Microsoft®
Windows®-based application that manages files and directories/folders.

file sharing
A
networked system that allows more than one user to access the same file.

file server
A computer that supports a
network of computers allowing them to communicate with one another and share resources.

file transfer protocol - FTP.
A common way to transfer files over the
Internet. FTP has been adapted to nearly all platforms and can be used in two modes: ASCII or binary.

finder
An essential component of the
Macintosh® system and loads with the system.

Firewire
A new, fasted
serial port that allows the chaining of devices. Firewire is faster than most parallel ports.

firmware
Software codes that are written directly and permanently onto chips.

first in/first out - FIFO.
A method of processing the first file in the order it was sent. Typically used with printer queues.

fixed width
As applying to fonts, fixed width fonts are
fonts whose characters take up the same amount of space independent of the specific character. For example, both an "i" and an "o" will take up the same amount of space even though the characters themselves are different widths. Variable width fonts (also called proportional fonts) are those fonts in which the characters take up different widths.

flash memory
Similar to
RAM except it does not lose its information when the power is shut off and is slower.

floating point operations per second - FLOPS.
A measure of the speed of computer. Floating point operations are mathematical calculations with floating point numbers.

floppy drive
Term used for the diskette drive. Diskettes are
disks with about 1.4 MB of storage.

FLOPS - floating point operations per second.
A measure of the speed of computer. Floating point operations are mathematical calculations with floating point numbers.

font
A set of characters, punctuation marks, and symbols. Fonts can be either scable (
TrueType® and PostScript® fonts) or of fixed point size.

format
1. To format a
disk to be compatible with a specific platform. Also called initialization of a disk.
2. The way text is arranged in a document with such formatting as columns, bold, font size, etc.

formula translation - FORTRAN.
FORTRAN is the oldest programming language, is not very
portable, is compiled, but fast. It has lost its appeal to other programming languages such as Java® and C++.

FORTRAN - formula translation.
FORTRAN is the oldest programming language, is not very
portable, is compiled, but fast. It has lost its appeal to other programming languages such as Java® and C++.

frame
A single image that can be displayed with a series of other frames to generate an animated image or video clip. Computer video often runs at 30 frames per second while film run at 24 frames per second.

freeware
software that is in the public domain and can be used free of charge.

frequently asked questions - FAQ.
A document that tries to answer frequently asked questions. This is a popular mode of support with the
world wide web.

FTP - file transfer protocol.
A common way to transfer files over the
Internet. FTP has been adapted to nearly all platforms and can be used in two modes: ASCII or binary.

full dump
A backup of an entire computer system's set of files. (See also
incremental dump.)

full-motion video
Frames that are usually displayed at 30 frames per second.

function keys
One of a dozen or more keyboard keys labeled F1, F2, etc. each have a specific pre-determined or programmed function such as copy, cut, paste, or print.



Show entire glossary || Download glossary
A B C || D E F || G H I J K || L M || N O P || Q R S || T U V W X Y Z


Sources:
"Everything you wanted to know about your Mac," Larry Hanson
Prentice Hall, Indianapolis, IN, 1993
ISBN: 1-56830-058-1

Matisse's Glossary of Internet Terms
Matisse Enzer
Copyright ©1994-2000

Microsoft® Corporation's Glossary and Acronyms
Microsoft® Corporation.
Copyright ©1999 All rights reserved.

The Network Page: Standard Computer-Term Glossary
Constructed as part of a course assignment for third year engineering students: An assessment of computer systems. Constructed at Sunderland University.

PC Cables Direct.Com's Computer Glossary Terms
PC Cables Direct, Inc.
3307 Langdon Road
Angier, N.C. USA 27501
Copyright ©1999

Saugus.net: Glossary of computer terms
Part of the Home Page for city of Saugus, MA
Copyright © 1998, 1999, 2000 Saugus.net

Sun Global Glossary Collection: Global Glossary
Sun Microsystems Inc.
901 San Antonio Road
Palo Alto, CA 94303
USA
Copyright ©1994-2000.

University of Chicago Campus Computer Stores
A Glossary of Computer Related Terms

University of Chicago
Copyright ©1997



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