Definitions Flashcards
Array
A finite, ordered set of elements of the same type.
Overflow
reached maximum size but trying to push
Underflow
empty but trying to pop.
Stacks
Items are added to the top of the stack and removed from the front.Used to hold return addresses when subroutines are called, when you press back in browser and undo in word processing.
List
An abstract data type consisting of a number of items which may occur more than once.
Pop
removing and returning an item from data strucutre
Push
Adding an item to a data structure
Queue
An ordered collection of items where new elements are added at the end of a queue and removed from the front of the queue. Used for waiting to print (queue on disk)
Dynamic Data Structure
A collection of data in memory that has the ability to increase or decrease in size while a program is running
Static Data Structure
A collection of data in memory that is fixed in size and cannot increase or decrease in size while the program is running.
Abstract data types
a data type created by the programmer rather than defined in a programming language.
Records
To store data permanently so you can read and update it at future dates. (Database)
Tuples
A dynamic data structure where the elements do not have to be the same type, and the number of elements in tuple can increase or decrease.
2-dimensional array
A collection of data items of the same data type Under one identifier but uses two index numbers. It can be represented as a table.
Compression
reduce the storage space of files on disk.
Lossy compression
non-essential information is removed from the original file.
Lossless compression
retains all information required to replicate the original file exactly.
Attribute
a property or characteristic of an entity.
Flat file database
consists of a single file (one entity).
Relational Databases
different entities in a system may be linked in some way, and the two entities are said to be related.
Primary Key
An entity’s unique identifier, normally a numeric ID.
Secodary Key
An index so that something can be quickly searched up. It would be quicker to search a secondary key like a name than a primary key ID.
Index
so that a record can be quickly located in the database an index is maintained so that it will give the position of each record. Primary keys and other things that are often searched (secondary keys) are indexed.
Foreign Key
the attribute that links the two entities/table (attribute that is common in both tables, can be more than one.)
Composite Primary Key
A primary key which consists of more than one attribute. (used when there is a many to many relationship between entities.)
Referral integrity
states relationships must be consistent, so when a primary key field changes so does the foreign key that has the link. And ensuring a primary key that is responsible for the link is not deleted
Normalisation
a process used to come up with the best possible design for a relational database.
Internet
is a network of networks set up to allow computers to communicate with each other globally, using the same protocol.
The World Wide Web (WWW)-
is a collection of web pages that resides on computers connected to the Internet.
Internet Service Providers
distributes internet connection to smaller providers who provide it to individual homes.
Uniform Resource Locators(URLs)
the full address of an Internet source.
Domain Names
identifies the area that an internet resource resides in
Domain Name System(DNS)
a hierarchical decentralized naming system for computers, services, or other resources connected to the Internet or a private network. It catalogues all domain names and has a table corresponding domain names to IP addresses
Internet Protocol (IP addresses)
A unique address that is assigned to a network device.
Wide Area Networks (WANs)
are distributed around different regions and can connect to multiple LANs. Also uses packet switching.
Local Area Networks (LANs)
Is small and local consisting of a number of computing devices on a single site, connected by cables.
Physical Bus Topology(Bus network)
in a LAN each node is connected to a main cable.
Physical topology
how the network is interconnected with wires and cables.
Logical topology
the communication mechanism for all nodes in a network and how they communicate across physical topology.
Wi-fi
a local area wireless technology that enables you to connect a device such as a PC to a network resource
Circuit switching
creates a direct link between two devices for the duration of the communication.
Packet switching
Splits data into packets and send the data across a network. There can be multiple transmission at different frequencies meaning the bandwidth is in constant use
Routers
used to connect to another network, traversing between them is called a hop.
Gateways
Going from one network to another network with a different protocol requires a gateway.
Media Access Control (MAC) addresses
Every computer device has NIC which has has its own MAC address which uniquely identifies the device.
Protocol
a set of rules defining common methods of data communication. These rules need to be standard across all devices in order for them to communicate to each other.
JavaScript
programs the behaviour of the web page
HTML
a language used for creating web pages and web applications. The code describes the content and structure of a web page.
CSS
a scripting language similar to HTML that is used to describe the layout and styles of a web page. (describes how HTML elements are to be displayed on screen, paper, or in other media).
Client-server networking
One or more computers are known as clients and are connected to a powerful central computer (the server). The client is dependent on the server to provide and manage the information, and all data is stored on the server. In a large network there may be many servers, each performing different tasks.
