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D/A converter: The processor on a sound card that converts the analog electrical signal into digital data.

daemon (pronounced "demon"): A UNIX program or agent designed to wait in the background while another program is running and execute only when required. Using a daemon, a program can simply hand off data to the smaller program and go on to more important things. For example, a print daemon could handle print requests from multiple users and applications, freeing them for other tasks.

daisy chain: The practice of connecting several MIDI devices together in a chain. Generally, the total length of the cables can extend up to 50 feet.

DAT (digital audio tape) recorder: A digital linear tape that uses PCM to convert analog signals into a digital form.

data rate: The throughput rate at which data can be sent from one device to another.

DAW (digital audio workstation): A computer that has been specially configured for work with audio.

decibel (dB): A measurement to measure sound pressure levels (dBSPL) or the voltage levels of an electrical audio signal (dBv).

dial-up modem: A device that gives your computer access to an external network by connecting to a serial port at a maximum speed of 56kbps.

DIMM (dual in-line memory module): A small circuit board that holds memory chips. Unlike SIMMS (single in-line memory modules), you can install memory one DIMM at a time.

digital signal processor (DSP): A chip that is designed to manipulate audio in real-time.

direct input (DI): The practice of plugging an instrument directly into a mixer or recording device. DI boxes and pre-amps are used to bring the instruments up to line level.

directory: A simulated file folder on disk. Programs and data for various applications (spreadsheets, word processing, etc.), are typically kept in separate directories. Directories create the illusion of compartments, but are actually links to files, which may be scattered all over the disk. UNIX and DOS use the term directory, while the Mac and Windows use the term "folder."

disk (or diskette): A random access, removable data storage medium that can be used with personal computers. The three main kinds of disks are diskettes, hard disks, and optical disks.

disk cache: High-speed, temporary, chip-based storage that reserves an area of RAM to store data that has been accessed from the hard drive. If the data is requested from the hard drive again, the computer gets it from RAM, which is much faster.

DivX (digital video express): A video rental system for digital versatile disks. For about $300 to $500, a user can purchases a DVD player that is equipped for Divx. The special Divx equipment includes a modem, a encryption microchip, and a proprietary flash memory. The user can then purchase Divx disks, which are essentially DVD-formatted disks that contain encrypted data. The user can play the disk within 48 hours of hitting the Play button. The user establishes a Divx account at the Divx website using a major credit card. The player automatically contacts the billing office once a month to update the account. This is the only time Internet access is required. The movie itself is played off-line.
dongle: A device developed to prevent piracy. It attaches to a port on your computer and works as a key to unlock a particular software application.

.DOC: A file extension for an MS Word file. In DOS and Windows environments, the file's type is specified by its three-character extension. For example, the .DOC extension identifies Microsoft Word documents. Once a file type has been associated with an application, selecting any file of that type automatically starts its associated application and loads the selected file.

domain name: The name that tells an Internet browser to go to a particular website. For example, TechTVs domain name is www.techtv.com.

dongle: A copy protection device that attaches to a computer to control access to a particular application. Also called a "hardware key." A dongle attaches to a PC's parallel port and prevents access to multiple copies of the same software. It is possible to attach several dongles to the same port.

DOS (disk operating system): The term DOS, promounced "dahss," can refer to any operating system, but it is most often used as shorthand for MS-DOS, the original operating system developed by Microsoft for the PC. MS-DOS is a single-user operating system, meaning it does not support multiple users or multitasking. MS-DOS began as the standard operating system for IBM-compatible personal computers and remained the underlying control program for all early Windows software up to version 3.1.

dpi (dots per inch): A measurement of printer resolution. The more dots per inch, the higher the resolution. A 400 dpi printer creates 160,000 dots (400x400).

DRAM (dynamic RAM): The most common type of RAM. It accesses information as it needs it, then closes and goes on to something else. Because DRAM is random, pieces of information can be stacked one upon another without discarding the entire stack. The information in DRAM is not only dynamic and randomly accessed, it's also fast. Today's processors handle information so fast they require a steady flow of information to optimize their capabilities. While hard drives offer plenty of storage space at a low cost per megabyte, their rotating parts and small buffering systems are too slow to keep up with the processor's need for input. Because DRAM is solid-state (with no moving parts), it can send data as fast as the processor can keep up with it.

DSL (digital subscriber line): A high-speed Internet-access connection that works over telephone networks and is available from 600Kbps to 26Mbps. Your maximum speed depends on your distance from the telephone provider's central office. The farther away you are, the slower it will be.

DV (digital video): The recording, editing, and storing of video in digital formats. A digital video (DV) camcorder is a video camera that captures and stores images on a digital medium such as a DAT or compact flash card.

DVD (digital video disk): A two-sided optical disc that holds a minimum of 4.7GB, enough for a full-length movie. DVDs can store significantly more data than ordinary CD-ROMs can, and can play high-quality videos.

DVD-R: DVD Recordable. Pioneer introduced the authoring use drive (635nm laser) in 1998. The general use format (650nm laser) was authorized in 2000. DVD-R offers a write-once, read-many storage format similar to CD-R. It's used to master DVD-Video and DVD-ROM discs.

DVD-RAM: DVD Random Access Memory. A rewritable DVD disc that is a cartridge-based, and more recently, bare disc technology for data recording and playback. DVD-RAM bare discs are fragile and do not guarantee data integrity. DVD-RAM Version 2 discs have double-sided 9.4GB discs. DVD-RAM drives typically read DVD-Video, DVD-ROM and CD media.

DVD-ROM: Read Only Memory. The disc stores data, interactive sequences, and audio and video. DVD-ROMs run in DVD-ROM or DVD-RAM drives, but not DVD-Video players connected to TVs and home theaters. Most DVD-ROM drives will play DVD-Video movies, however.

DVD-RW: DVD ReWritable. A rewritable DVD format that is similar to DVD+RW, but with less capability to work as a random access device. It has a read-write capacity of 4.7 GB.

dynamic microphone: A microphone that uses an electromagnetic coil. Generally, these microphones are less responsive than condenser microphones.

dynamic range: The difference between the loudest sound and the quietest sound that is produced or can be reproduced by a piece of equipment.

dynamics processor: A processor used specifically to control dynamic levels.

Don't see the word you want? Let us know at techglossary@techtv.com. For links to other resources, go back to the glossary's start page.

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