Informatics Alphabet; Glossary

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Term	Description
D/A	Converting the digital signal to analog. Converter that upon receipt of a sequence of binary pulses are calculated by how much value should be an analog signal and is set by calculating the output. The calculated value is retained until the next processing of the received sequence of binary pulses. If a sequence of pulses come faster if binary sequences contain a number of bits and hence a greater number of defined levels, the conversion was more or reconstructed analog signal closer to the original. How many levels and how fast depends on the conversion done and meant for, which is the number of levels higher and faster conversion device is expensive. For CD music tracks using 44.1 kHz sampling rate, with binary sequences of 16 bits.
Daemon	Program that works in the 'background' executing tasks for the user. They 'sleep' until something that needs their help. Most often the term used for the Unix / Linux operating systems. In Windows operating system programs the same dedicate called SERVICE. It is a service that is not basically a call while the computer is, the greater is operated at its inclusion and do not stop (never-end process). All of the above is nice while the operating system is not 'implant' some malicious programs were intended to permanently damage or waiting for a time bomb, and behaves in the manner described and appropriate name that does not act maliciously.
DAO	Disc-at-once - Refers to the way a CD recording with one session concluded. Option, does not exclude the laser recorder while recording data to the media. Finalize (closed) is a media content with 'Lead In' and 'Lead Out' entry, and no longer on it to record anything else, regardless of whether it is recorded all 700 MB or not. It is suitable for long continuous recording audio or video as a concert or a movie.
DAT	Digital Audio Tape - A tape with a magnetic strip that is kept in a box usual size L × W × H = 8 × 6 × 1.5 cm. Data stored on the tape is basically a record in segments that are arranged at an angle to each other, similar longitudinal slant fence or diagonally cut slices of cake or loaf of bread. The principle of operation is similar to the write mode video signal on a VHS tape. Write heads are located on the roller, which rotates and the axis of which the angle with respect to the strip in order to make writing 'diagonally'.
Database	An organized collection of data. One possible definition is that a database is a collection of records stored in a computer in a systematic way, so that a computer program can consult it to answer questions. Each entry is a better retrieval and sorting is usually organized as a set of elements (facts). The items retrieved in answer to queries become information that can be used for making decisions that might otherwise be much more difficult or impossible to create.
Data Integrity	Assumes the accuracy of the data transferred and basically refers to the authenticity of the sender and the possible unauthorized absence 'tampering' at what is sent, regardless of whether they are encrypted or not.
Data transfer rate	The speed at which data is transmitted or received via a communication channel with ignoring signs. If it is a duplex communication is not necessary to be in both directions at the same speed communication takes place. This term is not 'speed signal transmission', which is calculated based on the time duration of one pulse that carries one bit.
Debuging	Procedure for the correction of errors in the program code. Refer to the 'Bug'. Usually one correct mistakes made occasional new and need a reasonable period of time to 'almost all' mistakes removed. How soon that will be done depends on the number of developers who participate in the development of software, and the feedback from users. The program that no one uses no errors :-).
Default	Initial default variable as a program support, a record in the configuration of the operating system (such as the registry) or the default record in the computer's BIOS, or the action that will be performed on the default mode. If there is not another choice or default choice is impossible, will do a default task. They can also be defined as the default-parameters of any hardware manufacturer or software. Sometimes for the same term, the word 'preset', which usually means the act of divination to default parameters. Changing settings is possible by the intervention of the user. Changing the default settings, for example, the BIOS is usually used to increase the operating voltage and operating frequency components of the computer about achieving better performance of your computer, or say, increases the number of possible simultaneous TCP / IP connection to the operating system and the like.
DDC	Display Data Channel - A collection of protocols, for digital communication between a computer display and a graphics adapter, that enable the display to communicate its supported display modes to the adapter and that enable the computer host to adjust monitor parameters, such as brightness and contrast. The standard was created by the Video Electronics Standards Association (VESA). The DDC suite of standards aims to provide a 'Plug and Play' (PnP) experience for computer displays.
DES	Data Encryption Standard - Algorithm for encryption standard developed and standardized by the 'National Institute of Standards and Technology' (NIST - USA). Uses a secret 56-bit encryption key. DES algorithm is included in many encryption standards.
DHCP	Dynamic Host Configuration Protocol - Software for computer servers, which automatically delivers the IP address, network mask, and gateway IP address (the network output) when the computer it sends such a request. This eliminates the ability to manually assign addresses, and it is useful if not all computers accessing the network at the same time, but occasionally you do not have to use the correct number of IP addresses as there are computers, but much smaller. This is very interesting for the notebook. Assigned an address reserved for some time before being renewed or released, depending on whether or not the computer is left on the grid or not.
DHTML	Dynamic HTML - Can not be strictly considered as an extension of the HTML standard (because it is not), but requires a slightly different syntax respect to design HTML pages and enables small animations and dynamic menus using JavaScript and CSS. All Web content downloaded to the user's side and on her running.
DialUp	Program to connect the computer with the Internet service via modem communications dial certain phone number. In order to achieve communication on the access side there must be a server that will contain the user account and password to be able to monitor the rights that the user provides, as the price of access cost per unit of time, the longest living connections and the like.
Digest	Summary - An output of a hash function that creates a summary of messages in the process of creating digital signatures, which is the same size regardless of the size of the message.
Digital Certificate	Unique cryptographic signature, digital display attributes of users, services or equipment that is associated with a public key of identity. Certificate is unique and proves that the key is not compromised. The certificate is issued and signed by trusted certification institution, where the public key associated with the patent owner. Certification usually includes the name of the certificate owner, the owner of the public key, the serial number of the certificate and the date of expiry of the certificate. There may also be additional data. Certificates that have expired is not good to believe.
Digital Signature	Authentication method that allows easy detection of forgeries data and prevents proper rejection. In addition, the use of digital signatures is also verification that the transfer is done intact. Usually includes transfer time as a control parameter. If the time between transmission and reception of data longer than expected means possible someone to data kept by them 'messing'.
DLNA	Digital Living Network Alliance - Non-profit collaborative trade organization established by Sony, that is responsible for defining interoperability guidelines to enable sharing of digital media between multimedia devices. These guidelines are built upon existing public standards and specify a set of restricted ways of using the standards to achieve interoperability and include audio formats and video formats, meaning that DLNA servers generally have to support transcoding in order to produce a useful service. DLNA uses Universal Plug and Play (UPnP) for media management, discovery and control.
DMZ	Acronym for 'DeMilitarized Zone' - part of the local network (see intranet) that is located in a separate private subnet in which the mechanism through NAT addresses are translated into the public, but with traffic controls. Filtering of Internet traffic is a basic property of the DMZ.
DNS	Domain Name System - Communication between individual computers in the network is based on the principle of exchange of IP addresses. Remember what is behind some numbers very inefficiently. Therefore, the designed recognition system through the domain and host names. Each network is assigned a name (like 'buzdo.com'), and the computer assigns it to a name (such as Hope, Development, etc.) to some sort of systematization assign a name. Computer to a domain name assigned to its IP address in the DNS server table and the service allows translating them from one form to another. The entire Internet, which is also one large network, it uses the DNS mechanism.
DOCSIS	Data Over Cable Service Interface Specification - International telecommunications standard that permits the addition of high-speed data transfer to an existing cable TV system (CATV). It is employed by many cable television operators to provide Internet access over their existing Hybrid Fiber-Coaxial (HFC) infrastructure.
Domain name	A domain name is allocated according to the rules established by the International Organization for the award of the domain 'Internet Corporation for Assigned Names and Numbers'. So it was found several types of domains (com, net, edu ...) and individual states have their assigned codes for the domain (hr, ba, us ...). A domain name is assigned to the user according to his will if not already taken, and is separated from the type of item. This way we get a unique name to identify the user to the Internet regardless of the IP address of their server. DNS mechanism takes care to link the domain name with the IP address. With the domain can be defined and the computer name in the network, and his name will be on the Internet HOST_NAME.DOMAIN.TYPE. Sometimes instead of hostnames using a subdomain assigned to a directory server, and the name will be changed to SUB_DOMAIN.DOMAIN.TYPE.
DOS	Disk Operating System - Operating system developed by Microsoft, and are similar to his PC DOS, Free DOS versions of these and other species. Operating systems of this type do not have the graphical interface and for working with files using the command interpreter who can explain what to do when they write certain keywords associated with options. For more comfortable work used the 'utilities' to replace the write key words of which the most 'Norton Commander'.
Download	The download process data (files) by the user from a server connected to the Internet, and save them to disk users. It is useful to have a program called 'download manager' or something similar that they are able to download files in the case of the abort resume where they left off and collecting all the parts saved the downloaded file to a location that the user specifies.
DPI	Dots Per Inch - Number of dots per inch, which is most commonly used as a measure of quality of printing devices. In black-and-white printer indicates how individual black dots printed on the paper along the lines of length 1" (2.54 cm), and in the case of a print color refers to the number of pixels per unit length and then uses the label PPI - Pixels per Inch. higher the number of points / pixels per unit length can be made denser display, or display quality is higher. So, it is a description of the quality of printed images drawn or expressed as pixel density per unit length. U description of the device according to this density for the length and width of the square with a side of 1", and therefore can not be the same for couples side of the square (longitudinal and transverse).
DRAM	Dinamic Random Access Memory - Type of memory that data is kept as tidy a charge in a capacitor with which it achieves the kind of potential that can be recognized as a '1'. As the capacitor charges eventually lost due to leakage of insulators amount of charge has to be supplemented with time, and this procedure is called the refresh memory. On it loses part of its useful time and it takes time to charge or discharge the capacitor as this memory seems slow. Their advantage is that the monitoring of the capacitors should a transistor makes them cheap to produce.
Driver	Specially written program for a device that is installed in the computer. The purpose of this program is to cross the BIOS generated paths provide additional functionality to manage the device. Applies to printers, scanners, devices on the motherboard, video card and other. Graphics card games regarding the most dramatic example of how good or bad a driver affects the operation of the device, regardless of its capabilities. Instead of a nice choppy seas in Naval Submarine simulation result is a kind of smooth blue surface. It was stated in a much more well-there is no argument between drivers about sharing interrupts or memory resources.
DSLAM	Digital Subscriber Line Access Multiplexer - A device that is mounted on the side of the internet service provider (ISP) and allows for the device on the user communicates through a physical communication channel digital signal (DSL) rather than analog (modem). How to transfer the digital signal does not occupy the bandwidth of the physical channel as an analog signal, it is possible to send digital signals time-spaced for each time slot represents a 'logical channel', thereby increasing the overall throughput capacity of the physical channel.
DTE, DCE	According to the specification for serial communications (RS-232/422/485) defines the DTE ( Data Terminal Equipment) and DCE ( Data Communications Equipment) devices. DTE devices are terminals in the network structure as a computer, printer and other network with a reputation as a source or destination for the data. DCE are intermediate devices, like a modem, enabling connectivity to a physical network infrastructure. AUI port network card belongs to the DTE environment, and Transceiver that is connected to one of the DCE environment.
Duplex	Simultaneous two-way transmission of data one communication channel. At the same time the exchange of data takes place in both directions. This kind of communication is possible only in special cases, such as a telephone conversation, while you can speak and listen to the other person. Communication via mobile phone uses two separate subchannels within one channel.
DVB	Digital Video Broadcasting - A set of standards for digital broadcasting, or other form of digital signals. The final result of the application of these standards is the modulation amplitude of the high frequency signal digital signal process images QAM (Quadrature Amplitude Modulation), based on the parallel implementation of analog and digital signal transmission concept for message communication channel. Depending on the application developed standards DVB-T, DVB-C and DVB-S, which defines the signal transfer point terrestrial, cable, or satellite communication. Standards define the image resolution and aspect ratio display for SDTV (so far as the resolution of PAL and NTSC standards and aspect ratio 4:3) and HDTV (high definition 1280×720 pixels or 1920x1080 pixels and aspect ratio 16:9). Basic to all of the standards is that the content of image and sound are transmitted digitized. Systems for the distribution of HDTV picture resolution of 1920x1080 px branded DVB-T2, DVB-C2 and DVB-S2.
DVD	Digital Video Disk; Digital Versatile Disk - Optical media in physical dimensions and the size of the CD with the main purpose to save the movie video. The data is read by a red laser beam. And systems have been developed for one-time data recording (DVD-R and DVD+R) and rewritable data (DVD-RW), which use different technology than writing 'printed' DVD. Standard defines two recording layers on both sides giving a capacity of 4.7 GB, 8.54 GB, 9.4 GB and 17.08 GB.
DVD-RAM	Particular types of optical media and erase rewritable (RW), a basic-function similar to a floppy disk with a capacity of 2.32 GB or 4.7 GB, depending of standard on which they are made. The first value refers to the media placed in a box that is 'open' in a manner similar to a floppy disk of 3.5", and in another version it is a medium that is inserted into a conventional optical device. Electronic optical device must support this type of media that could be used. Its advantage is that it allows about 1000 times more RW operations compared to standard DVD-RW discs that support operations around 1000 rewrites.