IPT Glossary D

Question 1

DAC

Answer 1

Digital to Analog Converter

Question 2

Data Dictionary

Answer 2

A table identifying and describing the nature of each data item. Data dictionaries are used in many areas of system design, including the designs of databases.

Question 3

Data Flow

Answer 3

A labelled arrow on context and data flow diagrams describing the nature and direction of data movement.

Question 4

Data Flow Diagram

Answer 4

A Diagram that shows the logical flow of data through a system or subsystem

Question 5

Data Independence

Answer 5

The separation of data and its management from the software applications that process the data

Question 6

Data Integrity

Answer 6

A measure of how correct and accurately data reflects its source

Question 7

Data Mart

Answer 7

Reorganised summary of specific data extracted from s larger database. Data marts are designed to meet the needs of an individual system or department in an organisation

Question 8

Data Mining

Answer 8

The process of discovering non-obvious patterns within large collections of data

Question 9

Data Store

Answer 9

Where data is maintained prior to or after it has been processed. Data stores are represented as open rectangles on data flow diagrams.

Question 10

Data Verification

Answer 10

A check to ensure the data collected and stored matches and continues to match the source of the data.

Question 11

Data Validation

Answer 11

A check, at the time of of data collection, to ensure the data is reasonable and meets certain criteria.

Question 12

Data Warehouse

Answer 12

A large seperate combined copy of different databases used by an organisation. It includes historical data, which is used to analyse the activities of the organisation.

Question 13

Database Schemas

Answer 13

A technique for modelling the relationships within a relational database. Also known as Entity Relationship Diagrams (ERDs)

Question 14

DBMS

Answer 14

Database Management System

Question 15

Decision

Answer 15

A decision between two alternatives. Committing to one alternative over other alternatives.

Question 16

Decision Table

Answer 16

A tool for documenting the logic upon which decisions are made. They represent the rules, conditions and actions as a diagram.

Question 17

Decryption

Answer 17

The process of decoding encrypted data using a key

Question 18

Demodulation

Answer 18

The process of decoding a modulated analog wave back into its original digital signal. The opposite of modulation.

Question 19

Device Driver

Answer 19

A program that provides the interface between the operating system and a peripheral device.

Question 20

DFD

Answer 20

Data Flow Diagram

Question 21

Dial-Up Modem

Answer 21

A Modem used to transfer data over a traditional voice telephone line.

Question 22

Diary

Answer 22

A project management tool for recording the day-to-day progress and detail of completed tasks. Diaries tend to be used to record future appointments and factual information.

Question 23

Digital

Answer 23

Discrete. Digital data is coded and represented as distinct numbers. Computers use binary computer data.

Question 24

Direct Conversion

Answer 24

Completely replacing an old system with a complete new system at a particular point in time. Also called direct-cutover.

Question 25

Display Adapter

Answer 25

Synonym for Video Card

Question 26

Displaying

Answer 26

The information process that outputs information from an information system,

Question 27

Distributed Processing

Answer 27

Multiple CPUs used to perform processing tasks, often over a network and transparent to the user.

Question 28

DMD

Answer 28

Digital Micromirror Device. Used within DLP projectors.

Question 29

DMT

Answer 29

Discrete MultiTone. A modulation standard used by ADSL to dynamically assign frequencies.

Question 30

DNS

Answer 30

Domain Name Server. A server that determines the IP address associated with a domain name.

Question 31

DOCSIS

Answer 31

Data Over Cable Service Interface Specifications. The standards specifying communication over a cable network.

Question 32

Dot Pitch

Answer 32

The width of each pixel in mm. Commonly used to describe the resolution of screens.

Question 33

Downloading Distributed Database

Answer 33

A type of distributed database whereby each server download copies of data as it is required from remote databases and stores the data within its local data.

Question 34

DPI

Answer 34

Dots Per Inch. A measure of screen of printer output resolution.

Question 35

Draw Software Applications

Answer 35

A software application for manipulating vector images.

Question 36

DSL

Answer 36

Digital Subscriber Line

Question 37

DSLAM

Answer 37

DSL Access Multiplexor. A device at the telephone exchange that combines multiple signals from ADSL customers onto a single line to ISPs, and extracts individual customer signals from a signal line.

Question 38

DSP

Answer 38

Digital Signal Processor

Question 39

DVI

Answer 39

Digital Video Interface

Question 40

EFM

Answer 40

Eight to fourteen modulation. A system that converts each byte into fourteen bits such that all bit patterns include at least two but less than 10 consecutive zeros.