Glossary [D]

Term	Description
Default	That which is chosen by the Operating System or program if the user doesn't specify something different. E.g. default drive, default printer, default directory, etc..
Defragment	Your computer can slow down when files become fragmented. This means that the clusters the file is stored in are not physically next to each other on the disk. The read/write heads have to travel further to read the file. By defragmenting, files are rewritten to the disk in contiguous clusters thus speeding up data retrieval.
Desktop	When an Operating System that uses a Graphical User Interface (GUI) is finished loading, the screen that is initially displayed is called the Desktop. When you run a program or open a folder it appears in a window on the Desktop.
Device Driver	Individual programs can access communication ports or expansion slots either directly or via the OS or BIOS. However, there is such a vast number of different devices available to hook up to your computer that it can't be expected to know how to use the features of all of them. Most devices are shipped with small programs that are loaded onto your hard drive and tell the computer how to communicate with that specific input/output device whether it be a modem, printer, video card, etc.. These small software programs are called Drivers and are specific to each make and model of the device it comes with.
Diffuse	A technique to create a gray-scale image. Pixel patterns aren't set; they change gradually throughout the image.
DIMM	Dual Inline Memory Module. A small printed circuit board with memory chips on it. These modules clip into sockets on the motherboard to make up your system RAM. They come in denominations of 16, 32, 64, and 128 MB.
DIP Switch	A small switch on a circuit board or some other device that holds configuration or setup information for that device.
Directory	A table made by the Operating System that contains file information such as file name, size, date created, and the file's beginning cluster number.
Display Adapter	An adapter board or interface card that fits into a slot on the motherboard and controls the video signal sent to the monitor.
Dither	To create a gray-scale image by using fixed patterns of black and white pixels to represent each shade of gray. Every time the image needs a particular shade of gray, the software uses the same pattern.
DLL	Dynamic Link Library. A file that contains several small programs or routines that are common to many programs such as opening a window or saving a file. These library files have a .dll extension.
DMA	Direct Memory Access is an electronic pathway or direct channel on which a device can bypass the CPU and send data directly to memory. A DMA channel is often one of the resources assigned when configuring an expansion card or device such as a sound card.
Documentation	Manuals, tutorials, and Help files that provide information that a user needs in order to use a computer system or software application.
Domain	On TCP/IP networks, such as the Internet, a domain is a group of connected computers. Domains are identified on the Internet by a two or three letter code. Some of the most common are: .com - commercial site, .edu - educational institution, .gov - government site, .net - network site, .org - non-profit or private organization, .ca - a Canadian site. A domain can also refer to a group of workstations on a network. There can be sub-domains within a domain.
Domain Name	An identifying name given to a system or group of computers on a network. For example, the domain name computerstuff.com indicates that the domain is a commercial site (.com) and that the sub-domain name is computerstuff.
Dot Pitch	The distance between pixels of the same color on a monitor screen.
DRAM	Dynamic Random Access Memory. The most common type of system RAM. It comes in several different flavors, EDO, FPM, SDRAM. It uses less space, less power, and is cheaper than static RAM, but it has to be refreshed every millisecond or it loses its information.
Driver	See Device Driver.
DriveSpace	DriveSpace is a Microsoft utility that is supposed to increase the amount of space on your hard drive. What it actually does is compress the files on your drive and create a single large file that contains all the compressed. The compression and decompression takes place in the background, unnoticeable to the user.
Dual Boot	The ability to boot your computer using one of two different operating systems.
Dual Voltage CPU	A Central Processing Unit that requires two different voltages, one for external functions and one for internal processing.
DVD	Digital Video Disk. A type of CD-ROM format that is faster and can hold more data than a regular CD-ROM. It still has the ability to read older CDs, but a DVD disk can hold more than 8 gigabytes (as opposed to 750 Mb) and can display full-motion picture videos.
Dynamic RAM	See DRAM.

Glossary [E]

Term	Description
E-zine	Electronic Magazines are short online journals written for the Internet that take advantage of the low publishing cost of the World Wide Web.
Easter Egg	Programmers sometimes put pieces of code into an application that produce unexpected surprises. Users usually won't see them unless they press a certain key combination. They're usually found by word of mouth and rarely by accident.
Edge Connector	Found along one side of an expansion card, the little metal connectors that transmit data and other signals to your computer through the bus slot that it fits into.
EDO RAM	Extended Data Out RAM. A type of DRAM that can be 10% to 20% faster than normal DRAM if no external cache is used. EDO keeps its chip output buffer open longer and can begin to access more data even before its done reading the previous data. Not much of a speed increase is noticed over Fast Page Mode RAM if an external cache of 256K is present. Controller must be compatible or it will act like normal DRAM.
EEPROM	Electronically Erasable Programmable Read Only Memory. A type of ROM chip that can be electronically erased and reprogrammed in circuit using software. The introduction of EEPROM allowed expansion devices to be configured using software instead of jumpers and DIP switches.
EGA	Enhanced Graphics Adapter. A high resolution video card that came out after CGA. It was manufactured by IBM and could produce a resolution of 640 X 350 pixels and display 16 colors out of a palette of 64.
EIDE	Enhanced Integrated Drive Electronics. Improved version of the IDE interface for hard drives and CD-ROMs. EIDE uses Logical Block Addressing which allows for HD capacities over 528 MB. It makes use of Direct Memory Access and can address up to four devices. Also called Fast ATA.
EISA	Extended Industry Standard Architecture. The standard for an IBM compatible computer data bus that can transfer 32 bits of data at a time. Extended ISA was developed in response to IBM's proprietary Micro Channel Architecture bus (MCA). Unlike MCA, it was backwards compatible with the older 16 bit ISA bus.
Electrostatic Discharge	See ESD.
EMM386.EXE	A DOS Extended Memory Manager utility that provides access to upper memory blocks and can use Extended Memory to emulate Expanded Memory for the older DOS programs that require it.
Energy Star Systems	Systems that satisfy the EPA requirements to decrease the overall consumption of electricity. "Green Systems".
Enhanced BIOS	A newer BIOS that has been written to accommodate larger-capacity (gigabyte) drives.
Enhanced Graphics Adapter	See EGA.
EPROM	Erasable Programmable Read Only Memory. A type of PROM chip that can be removed from the circuit and erased using ultraviolet light. The chip can then be re-programmed using an EPROM burner.
ESD	Electrostatic Discharge is the discharge of built up static electricity. You may not even feel the discharge but ESD can damage chips and ruin motherboards, rendering your computer useless.
Expansion Card	An electronic circuit board that fits into a slot on your motherboard expanding the capabilities of your computer. i.e.: video card, internal modem, sound card.
Expansion Slot	A connector or slot on your computers motherboard that allows for the insertion of an expansion card, connecting it to the systems bus or electronic pathways.
Extended Data Out RAM	See EDO RAM.
Extended Graphics Array	See XGA.
Extended Memory	See XMS.
Extended Technology	See XT.