D
* D/A Converter
* DAA: Data Access Arrangement
* DAC: Digital-to-Analog Converter
* DACS: Digital Access and Cross-connect System
* Daisy Wheel Printer
* Dark Fiber
* DAS: Direct Attached Storage
* Data Cartridge
* Data Processing
* Data Projector
* Database Server
* Daughtercard or Daughterboard
* DB Connector: Database Bus connector
* DDC: Digital Down Converter
* DDC: Display Data Channel
* DDR Memory: Double Data Rate Memory
* DDR:Double Date Rate
* DDR-2: Double Data Rate Two
* DDR2-SDRAM: Double Data Rate 2 Synchronous Dynamic Random Access Memory
* DDRAM: Double Data Rate Random Access Memory
* DDR-SDRAM: Double Data Rate-Synchronous DRAM
* Dead Pixel
* Decoder
* Demarcation Point
* Desktop Computer
* DDB: Device Dependent Bitmap
* Device Programmer
* DIB: Device-Independent Bitmap
* DIB: Dual Independent Bus
* Digital Filter
* Digital Monitor
* DSP: Digital Signal Processor
* DSPWare
* DVI: Digital Visual Interface
* DIN Connector: Deutsche Industrie Norm Connector
* DIP Switch: Dual-Inline Package Switch
* Direct Thermal
* Direct-Connect Modem
* DirectX
* Disk
* Disk Access
* Disk Cache
* Disk Drive
* Disk Format
* Display Adaptor
* Display Screen
* DIVX: Digital Video Express
* DLC: Data Link Control
* DLP: Digital Light Processing
* DLT: Digital Linear Tape
* Dongle
* Dot Matrix Printers
* Dot Pitch
* DPMI: DOS Protected Mode Interface
* DPMS: Display Power Management Signaling
* DPMS: Display Power Management System
* DRAM: Dynamic Random Access Memory
* DSLAM: Digital Subscriber Line Access Multiplexer
* DSP: Digital Signal Processing
* DSTN: Double-layer Super-Twist Nematic
* DIMM: Dual In-line Memory Module
* DIP: Dual In-line Package
* Dual-Core
* Dual-Homed Host
* Dual-Processor
* Dual-Scan Display
* DUC: Digital Up Converter
* Dumb Terminal
* Duplexer
* DVD-Video
* Dvorak Keyboard
D/A converter
Digital-to-Analog converter, also known as D/A converter, DAC or D-to-A, is a device that convert a set of bits from a processor to an analog signal (current, voltage or charges) according to the digital input. D/A converters might be as simple as an array of resistors configured in the typical "R-2R" fashion or a hybrid module that generates very precise results with many bits of resolution. Simple switches, a network of resistors, current sources or capacitors may implement this conversion.
DAA: Data Access Arrangement
Data Access Arrangement(DAA) provides the analog circuits that electrically isolate the modem from the phone line, separating the modem from the telephone line higher voltage. The FCC requires this feature of any device that connects to the PSTN, including fax machines and set-top boxes, and most manufacturers build modems around an FCC-approved DAA design.
DAC: Digital-to-Analog converter
Digital-to-Analog converter (DAC), also known as D/A converter, or D-to-A, is a device that convert a set of bits from a processor to an analog signal (current, voltage or charges) according to the digital input. D/A converters might be as simple as an array of resistors configured in the typical "R-2R" fashion or a hybrid module that generates very precise results with many bits of resolution. Simple switches, a network of resistors, current sources or capacitors may implement this conversion.
DACS: Digital Access and Cross-connect System
Digital access and cross-connect system (DACS, DCS or DCCS) is a digital switching device in telecommunications for routing T1 lines. The DACS can cross-connect any T1 line in the system with any other T1 line also in the system. DACS is a simple form of channel switch which works at the DS0, DS1(T1/E1) and DS3(T3/E3), as well as STS-level.
Daisy Wheel Printer
A daisy wheel printer is a type of computer printer that produces high-quality type, and is often referred to as a letter-quality printer (this in contrast to high-quality dot-matrix printers, capable of near-letter-quality (NLQ) output). To print a character, the printer rotates the disk until the desired letter is facing the paper. Then a hammer strikes the disk, forcing the character to hit an ink ribbon, leaving an impression of the character on the paper. You can change the daisy wheel to print different fonts. There were also, and still are daisy wheel typewriters, based on the same principle.
dark fiber
Dark fiber refers to unused fiber-optic cable that have been laid out in the field. Often times companies lay more lines than what's needed in order to curb costs of having to do it again and again. The dark strands can be leased to others who want to establish optical connections among their own locations.
DAS: Direct Attached Storage
Direct Attached Storage (DAS) is a storage device directly attached to a host system, such as the internal hard drive of a server computer. DAS is still, by far, the most common method of storing data for computer systems.
data cartridge
A data cartridge is used to hold computer data. There are many designs and manufactures for data cartridges. For example, 4mm data tape cartridge is one of the design for data back up.
data processing
Data processing is a computer process that converts data into required information. The processing is usually assumed to be automated and running on an a computer. There are many data processing applications, such as accounting programs that converts raw financial data into meaninful reports for various purpose. Another example is customer relationship management systems (CRM) and employee relationship data systems.
data projector
Data projector is a device that projects whatever is on the computer's display onto a big screen.
Database server
A database server is a computer program that provides database services to other computer programs or computers, as defined by the client-server model. The term may also refer to a computer dedicated to running such a program. Database management systems frequently provide database server functionality, and some DBMS's (e.g., MySQL) rely exclusively on the client-server model for database access.
daughtercard or daughterboard
Daughtercard, also known as daughterboard, is a printed circuit board meant to be an extension or "daughter" of a motherboard (or 'mainboard'). Daughterboards often have plugs, sockets, pins, connectors, or other attachments for other boards, which is what differentiates them from a standard expansion board such as for PCI or ISA. In addition, daughterboards usually have only internal connections within a computer or other electronic device rather than any external ones, and usually access the motherboard directly rather than through a computer bus.
DB Connector: Database Bus connector
Database Bus connector (DB connector), defined by various EIA/TIA standards, is a type of connectors used to connect serial and parallel cables to a data bus. DB connector names are in the format of DB-x, where x represents the number of (wires) within the connector. Each line is connected to a pin on the connector, but in many cases, not all pins are assigned a function. DB connectors come in 9, 15, 25, 37 and 50-pin sizes. The DB connector defines the physical structure of the connector, not the purpose of each line. For example, DB-9 connectors have 9 pins and are used to connect a mouse. DB-25 connectors have 25 pins and are used to connect a printer.
DDC: Digital Down Converter
Digital down-converter (DDC), a key component for digital radio and 3g communications, performs the critical frequency translation needed to recover the information from a digitized modulated signal. DDC is typically used in wireless and wireline communication systems to perform channel access functions in all-digital receivers. See also Digital Up Converter (DUC).
DDC: Display Data Channel
Display Data Channel (DDC) is a digital connection between a computer display and a graphics adapter that allows the display to communicate its specifications to the adapter. The standard was created by VESA. Using DDC, a monitor can inform the video card about its properties, such as maximum resolution and color depth. The video card can then use this information to ensure that the user is presented with valid options for configuring the display.
DDR memory: Double Data Rate memory
DDR memory, or Double Data Rate memory, is an evolutionary new memory technology that doubles data throughput to the processor. As an evolution of SDRAM, DDR memory leverages the existing production and environment to provide better PC performance at an affordable price. DDR memory is also known as DDR-SDRAM, or DDRAM.
DDR:Double Date Rate
Double Date Rate (DDR) memory, also known as DDR-SDRAM, is an enhanced type of SDRAM that supports data transfers on both edges of each clock cycle, effectively doubling the memory chip's data throughput. DDR-SDRAM also consumes less power, which makes it well-suited to notebook computers.
DDR-2: Double Data Rate Two
Double Data Rate Two (DDR-2), also known as Double Data Rate Two Synchronous Dynamic Random Access Memory(DDR2 SDRAM), is a computer memory technology that, as of 2005, is becoming the mainstream standard for personal computer memory. DDR2 is part of the SDRAM family of random access memory technologies, which is itself one of many DRAM implementations. The advantage of DDR-2 over DDR SDRAM is its ability to run at much higher clock speeds due to an improved electrical interface.
DDR2-SDRAM: Double Data Rate 2 Synchronous Dynamic Random Access Memory
Double Data Rate 2 Synchronous Dynamic Random Access Memory(DDR2-SDRAM), also known as DDR-2, is the improved version of DDR-SDRAM. DDR2-SDRAM offers greater bandwidth and density in a smaller package along with a reduction in power consumption. In addition DDR2-SDRAM offers new features and functions that enable higher a clock rate and data rate operations. DDR2 transfers 64 bits of data twice every clock cycle. DDR2-SDRAM memory is not compatible with current DDR-SDRAM memory slots.
DDRAM: Double Data rate Random Access Memory
Double Data rate Random Access Memory(DDRAM), also known as DDR-SDRAM, reads data on both the rising and falling edge of the clock, achieving a faster data rate. Often used in notebook computers because it also consumes less power.
DDR-SDRAM: Double Data Rate-Synchronous DRAM
Double Data Rate-Synchronous DRAM (DDR-SDRAM), also known as SDRAM II, is an enhanced type of SDRAM that supports data transfers on both edges of each clock cycle, effectively doubling the memory chip's data throughput. DDR-SDRAM also consumes less power, which makes it well-suited to notebook computers.
dead pixel
A pixel on an LCD monitor that can not be lighted or activated. It occurs because the transistor that activates the amount of light malfunctions and results in a permanently black pixel.
decoder
Decoder is a hardware device or a software program that translates a coded signal back to its original form. Decoders are used in many different ways such as to enable a computer to recognize instructions and addresses, or help programers to troubleshoot network applications.
demarcation point
Demarcation Point, also known as point of demarcation (POD), is the network point or joint at which the public network of a telecommunications company ends and the private network of a customer begins.
Desktop computer
A desktop computer is a personal computer that is made especially for use on a desk in an office or home. In addition to the PCs running Windows OS systems, Macintoshes and UNIX workstations are also considered desptop computers.
device programmer
Device Programmer is a type of tool for programming EPROMs, PLDs, nonvolatile memories, and other electrically programmable devices and chips. Typically, the programmable device is inserted into a socket on the device programmer, and the contents of a memory buffer are then transferred into it. Gang programmers, a type of device programmer, is capable of programming multiple devices from the same image simultaneously.
DIB: Device-Independent Bitmap
Device-Independent Bitmap (DIB), also kown as Bitmap (BMP), is the graphics format supported by Windows and some other OS. The graphic files in DIB format are generally end with a .bmp extension. DIB images can also be transferred in metafiles and the clipboard. It's called device-independent because colors are represented in a format independent of the final output device. When a DIB image is output to a specific device, the device driver translates the DIB colors into actual colors that the output device can display. For example, to display bitmap graphs on screen, Device Dependent Bitmap (DDB) must be used.
DIB: Dual Independent Bus
DUAL INDEPENDENT BUS (DIB) architecture is introduced in the Intel's Pentium II to connect the processor, memory, and L2 cache. One bus connects the processor to L2 cache and a second connects the processor to main memory. Having two buses instead of one increases performance over single-bus architectures. In addition, the speed of the external L2 cache can scale up independently from the speed of the system bus.This allows for faster cache access. The final feature of the DIB architecture is a pipeline on the cache to the processor bus that allows multiple simultaneous cache requests.
Digital Filter
A digital filter uses a digital processor to perform numerical calculations on sampled values of the signal. The processor may be a general-purpose computer such as a PC, or a specialised DSP (Digital Signal Processor) chip. A digital filter accepts digital inputs (typically samples read from an A/D converter) and produces digital outputs - and filtering unwanted signal during the process.
digital monitor
Digital Monitor accepts digital signal and changes it to analog for display. Unlike a analog monitor a digital monitor is not capable of displaying an infinite range of colors. All monitors (except flat-panel displays) use CRT technology are basically analog. The term digital, therefore, refers only to the type of input received from the video adapter. A digital monitor then translates the digital signals into analog signals that control the actual display.
DSP: Digital Signal Processor
Digital Signal Processor (DSP) is a device, typically a chip or microprocessor, in which the internal CPU has been optimized for use in applications involving discrete-time signal processing. In addition to standard microprocessor instructions, DSPs usually support a set of specialized instructions, like multiply-and-accumulate, to perform common signal-processing computations quickly.
DSPWare
DSPWare is a firmware running on the DSP coprocessor.
DVI: Digital Visual Interface
Digital Visual Interface (DVI), based on the standard created by the Digital Display Working Group (DDWG), is a video connector designed to maximize the visual quality of digital display devices such as flat panel LCD computer displays and digital projectors. DVI converts analog signals into digital signals to accommodate both analog and digital monitors. DVI handles bandwidths in excess of 160 MHz and thus supports UXGA and HDTV with a single set of links.
DIN Connector: Deutsche Industrie Norm Connector
Deutsche Industrie Norm connectors (DIN Connector) are 13.2 mm in diameter, and are available in patterns with three to fifteen pins. DIN Connector are used in some Macintosh and IBM PC-compatible computers, and on some network processor panels. For example, the keyboard connector for PCs is a DIN connector. DIN 41612 connectors are used widely to connect network equipment, such as routers and switches.
DIP switch: Dual-Inline Package switch
Dual-Inline Package (DIP) switch is an electric switch. Because of the DIP form factor, arrays of multiple DIP switches can easily be incorporated into the same package. This type of switch is designed to be used on a printed circuit board along with other electronic components and is commonly used to customize the behavior of an electronic device for specific situations. DIP switches enable you to configure a circuit board for a particular type of computer or application. The installation instructions should tell you how to set the switches. DIP switches are always toggle switches, which means they have two possible positions -- on or off.
direct thermal
Direct Thermal is a type of printing technology that prints the image by burning dots onto coated paper when the paper passes over a line of heating elements. Early fax machines used direct thermal printing. It is also used to print labels and bar codes.
direct-connect modem
Direct-connect modem connects directly to a telephone line via modular connectors rather than requiring an acoustic coupler. Almost all modern modems are direct-connect.
DirectX
DirectX, provided by Microsoft, is a suite of multimedia application programming interfaces (APIs) built into Microsoft Windows OS. DirectX provides a standard development platform for Windows-based PCs by enabling software developers to access specialized hardware features without having to write hardware-specific code. The DirectX APIs give multimedia applications access to the advanced features of high-performance hardware such as three-dimensional (3-D) graphics acceleration chips and sound cards. They control low-level functions, including two-dimensional (2-D) graphics acceleration; support for input devices such as joysticks, keyboards, and mice; and control of sound mixing and sound output. Because of DirectX, what you experience with your computer is better 3-D graphics and immersive music and audio effects.
disk
In the cotext of computer hardware, disk is a round shaped media to store computer data. There are two basic types of disks: magnetic disks and optical disks. On magnetic disks such as the compuer hard driver, data are encoded as microscopic magnetized needles on the disk's surface. You can record and erase data on a magnetic disk any number of times.
disk access
Disk Access refers to read from and write to a computer disk. The disk access time is the average of the time it takes to position the head over the requested track.
disk cache
A disk cache is a mechanism for improving the time it takes to read from or write to a hard disk. The disk cache can be part of RAM (sometimes called a soft disk cache) or part of the hard disk(sometimes called a hard disk cache or buffer). The disk cache holds data that has recently been read and, in some cases, adjacent data areas that are likely to be accessed next. Write caching is also provided with some disk caches. Hard disk caches are more effective, but they are also much more expensive, and therefore smaller.
disk drive
Disk Drive is a peripheral device that reads and writes disks. There are different types of disk drives for different types of disks. For example, a hard disk drive (HDD) reads and writes hard disks, and a floppy drive (FDD) accesses floppy disks. A magnetic disk drive reads magnetic disks, and an optical drive reads optical disks. The drive typically contains a motor to rotate the disk at a constant rate and one or more read/write heads which are positioned over the desired track by a servo mechanism. It also contains the electronics to amplify the signals from the heads to normal digital logic levels and vice versa.
Disk Format
Disk formatting is the process of preparing a hard disk or other storage medium for use with the file system of an operating system. Formatting a drive (or partition) effectively destroys all data it contains. For this reason, before formatting any disk, backups of vital data should be taken; a computer with a corrupted operating system can be reverted to a fresh state by formatting the disk again and installing the operating system on the newly formatted disc. A formatting of a disk involves two quite different processes that have come to be known as "low-level formatting" and "high-level formatting." Low-level formatting deals with formatting of disk surfaces required by the disk controller hardware; high-level formatting deals with software-specific information written by a specific operating system.
display adaptor
Display adaptor, also known as Graphics card, graphics accelerator, video card, video board, video display board, video adapter, or graphics adapter. It is a component of a computer to convert a logical representation of an image stored in memory to a signal that can be used as input for a display medium, most often a monitor utilising a variety of display standards. The graphics card may be a stand-alone expansion card but is often also built into the computer.
display screen
Display screen is the display area of a computer monitor.
DIVX: Digital video express
Digital video express (DIVX) is a DVD-ROM format based on the MPEG-4 technology promoted by several Movie companies. The DivX codec can compress video to a convenient size without losing much quality and play those videos back on almost any device. To fight against piracy, with Divx, a movie (or other data) loaded onto a DVD-ROM is playable only during a specific time frame, typically two days. As soon as you begin playing a Divx disc, the counter starts.
DLC: Data Link Control
Data Link Control (DLC) is the service provided by the Data Link Layer at the second lowest layer in the OSI Reference Model. Every network interface card (NIC) has a DLC address or DLC identifier (DLCI) that uniquely identifies the node on the network. For example, Ethernet and Token-Ring use the DLC addresses with a 48 bits number and it is also called MAC address.
DLP: Digital Light Processing
Digital Light Processing (DLP), developed by Texas Instruments, is used for projecting images from a computer monitor onto a large screen for presentations. Prior to the development of DLP, most computer projection systems were based on LCD technology which tends to produce faded and blurry images. In DLP projectors, the image is created by microscopically small mirrors laid out in a matrix on a semiconductor chip, known as a Digital Micromirror Device (DMD). Each mirror represents one pixel in the projected image. These mirrors can be repositioned rapidly to reflect light either through the lens or on to a heatsink (called a light dump in Barco terminology).
DLT: Digital Linear Tape
Digital Linear Tape (DLT), originally developed by Digital Equopment for its VAX computers and now owned by Quantum, is a de facto standard for magnetic tape technology used for computer data storage. DLT uses half-inch, single-hub cartridges. It writes 128 or 208 linear tracks, depending on model, and provides native capacities from 40 to 80GB. Linear Tape-Open (or LTO) is a competing technology by IBM and HP etc.
dongle
In computer networking, a dongle is a short network cable that joins a PCMCIA adapter to a network cable. A dongle is used as a security key and its purpose is to ensure that only authorized users can use certain software applications or data. Dongles typically attach to either a RJ-45 connector for Ethernet networking or an RJ-11 connector for dial-up networking. The term "dongle" also has become popular in USB networking, referring to the USB cable that extends from a USB peripheral.
Dot Matrix Printers
Dot Matrix Printer is a type of printers preceding inkjet or laser printers, which uses a set of pins strike against an inked ribbon resulting in characters forming on the underlying paper. The printing quality of dot matrix printers depend on the number of pins from 9, very low, to 48 almost letter quality. These printers are generally fed from a continuous roll of paper and still lend themselves to report printing and long banners. Dot Matrix Printers can print to multi-page forms (that is, carbon copies), something laser and ink-jet printers cannot do.
dot pitch
Dot Pitch, also knowns as phosphor pitch, is a measurement of how sharp the display image can be. Measured in millimeters (mm), it indicates the diagonal distance between like-colored phosphor dots on a display screen. Typically numbers are in the range of 0.15mm to 0.31mm and a smaller number of the Dot Pitch means a sharper image. A pixel is the smallest programmable visual element and maps to the dot if the display is set to its highest resolution. When set to lower resolutions, a pixel encompasses multiple dots.
DPMI: DOS Protected Mode Interface
Created for Windows version 3.0, DPMI is an industry standard for an interface that allows DOS applications to access extended memory of the 80286-, 80386-, and 80486-based PC architecture while maintaining system protection.
DPMS: Display Power Management Signaling
Display Power Management Signaling (DPMS) is a VESA interface standard that reduces power to computer monitors, when not in use. DPMS defines four power management modes for monitors in idle state: on, stand-by, suspending and off. Using DPMS, the display controller (typically the video card or chip from which the monitor receives signals) sends a signal along two signal lines: horizontal sync (h-sync) and vertical sync (v-sync) -- to the monitor, instructing it to enter into one of the four power management states.
DPMS: Display Power Management System
Display Power Management System (DPMS) is a system that reduces the amount of energy consumed by a monitor when it's idle. DPMS is used to selectively shut down parts of the monitor's circuitry after a period of inactivity. With a motherboard and monitor that support DPMS, power consumption can be greatly reduced. Motherboards that support DPMS often have a BIOS setting to enable it.
DRAM: Dynamic Random Access Memory
Dynamic Random Access Memory (DRAM), a type of memory used in most personal computers, stores each bit of data in a separate capacitor based on semi-conductor. The number of electrons stored in the capacitor determines whether the bit is considered 1 or 0. As the capacitor leaks electrons, the information gets lost eventually, unless the charge is refreshed periodically. Because it must be refreshed periodically, it is a dynamic memory as opposed to Static Random Access Memory (SRAM) and other static memory. Also, since DRAM loses its data when the power supply is removed, it is in the class of volatile memory devices.
DSLAM: Digital Subscriber Line Access Multiplexer
Digital Subscriber Line Access Multiplexer (DSLAM) is a device that aggregates many customer DSL connections to a single high-speed ATM line to the backbone network. When the phone company receives a DSL signal, an ADSL modem with a POTS splitter detects voice calls and data. Voice calls are sent to the PSTN, and data are sent to the DSLAM, where it passes through the ATM to the Internet, then back through the DSLAM and ADSL modem before returning to the customer's PC.
DSP: Digital Signal Processor
Digital Signal Processor (DSP) is a device, typically a chip or microprocessor, in which the internal CPU has been optimized for use in applications involving discrete-time signal processing. In addition to standard microprocessor instructions, DSPs usually support a set of specialized instructions, like multiply-and-accumulate, to perform common signal-processing computations quickly.
DSTN: Double-layer Super-Twist Nematic
Double-layer Super-Twist Nematic (DSTN) is a passive-matrix LCD technology. DSTN uses two display layers to counteract the color shifting that occurs with conventional supertwist displays to improve visibility. In other words, DSTN is an improved version of the standard supertwist nematic passive matrix LCD screen.
DIMM: Dual In-line Memory Module
Dual In-line Memory Module (DIMM) is a small circuit board that holds memory chips. DIMM is double SIMM (Single In-line Memory Module), which has a 32-bit path to the memory chips whereas a DIMM has 64-bit path. DIMMs began to replace SIMMs as the predominant type of memory module when Intel's Pentium processors were in the mainstream market.
DIP: Dual In-line Package
Dual In-line Package (DIP), also known as DIL package, is a type of chip housed in a rectangular casing with two rows of connecting pins on either side. A DIP is usually referred to as a DIPn, where n is the total number of pins. DIPs may be used for integrated circuits (ICs, "chips"), like microprocessors, or for discrete components such as resistors or toggle switches.
dual-core
Dual-core refers to a microprocessor (CPU) that includes two complete independent processors and their respective caches and cache controllers in one physical chip. Various dual-core CPUs are being developed by companies such as IBM, Motorola, Intel and AMD, and began to appear in consumer products in 2005. Dual-core processors are well-suited for multitasking environments, since each core has its own cache, the operating system has sufficient resources to handle most compute intensive tasks in parallel.
dual-homed host
Dual Homed Host refers to a host computer that participates in two separate networks. A dual-homed host can provide security functions as a firewall that uses two (or more) network interfaces. One connection is an internal network and the second connection is to the Internet.
dual-processor
A traditional dual processor system contains two separate physical computer processors in the same chassis. The two processors are usually located on the same circuit board (mother board) but occasionally will be located on separate circuit boards. A dual-processor (DP) system can also be considered a subset of the larger set of a symmetric multiprocessor (SMP) system. A multi-processor capable operating system can schedule two separate computer processes or two threads within a process to run simultaneously on these separate processors.
dual-scan display
Dual Scan Display is a type of passive-matrix display that refreshes twice as often as the regular passive-matrix and the top and bottom half of the screen are refreshed simultaneously. Dual-scan displays are not as sharp or bright as active-matrix displays, but they consume less power.
DUC: Digital Up Converter
Digital Up Converter(DUC), a key component for digital radio and 3G communications, is a digital circuit which implements the conversion of a complex digital baseband signal to a real passband signal. The input complex baseband signal is sampled at a relatively low sampling rate, typically the digital modulation symbol rate. The baseband signal is filtered and converted to a higher sampling rate before being modulated onto a direct digitally synthesized (DDS) carrier frequency. The DUC typically performs pulse shaping and modulation of an intermediate carrier frequency appropriate for driving a final analog upconverter and is used extensively in wireless and wireline communication systems.
dumb terminal
Dumb terminal refers to the display monitor that has no intelligence and processing capabilities but simply an input/output device that accepts data from the CPU and user. Dumb terminal consists of a computer screen and keyboard. They allow a user to carry out work on a remote server, minicomputer or mainframe. They have largely been superseded by personal computers which can perform lots of local data processing. On the other hand, smart terminals and intelligent terminals with certain processing power are used in some special situations such as graphics processing.
duplexer
Duplexer has multiple meanings depends on where it is used. In tele-communication, a duplexer is a device that combines two or more signals onto a common channel or medium to increase its transmission efficiency. In radar systems, Duplexer is a device that isolates the receiver from the transmitter while permitting them to share a common antenna. In printer, duplexer is a add-on component that allows for both sides of a page to be printed at the same time.
DVD-Video
DVD-video is a digital video format for displaying full-length digital movies. Unlike DVD-ROMs, the Digital-Video format includes a Content Scrambling System (CSS) to prevent users from copying discs. DVD-ROM players cannot play DVD-Video discs without a software or hardware upgrade to decode the encrypted discs.
Dvorak keyboard
Dvorak keyboard is designed for speed typing by August Dvorak. Unlike the traditional QWERTY keyboard, the Dvorak keyboard is laid out to have the middle row of keys with the most common letters. In addition, common letter combinations are positioned in such a way that they can be typed quickly.