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Computing Revision 1.3 - Coggle Diagram
Computing Revision 1.3
Casting - Used to change one data type into another.
Variable - Used to store data whilst the program is running.
Constant - Store data but their values are fixed and can't change whilst the program is running.
Variable identifiers - Start with a letter, can contain numbers and symbols but no spaces.
Concatenation - Adding 2 strings together.
Logic Gates - Digital circuits which have more than one input but only one output.(AND,OR,NOT)
Denary - Base 10 - 9 digits available.
Binary - Base 2 - 2 digits available.
Hex - Base 16 - 16 digits available(0-9 and A-F)
Binary Shift - binary number is moved either left or right. Right shift means divide and left shift means multiply.
Images - Made up of pixels. Each pixel is a single colour.
Resolution - Concentration of pixels = higher resolution means a better quality of image but a larger file size.
Colour depth - The colour of a pixel is stored as a binary number. The number of binary digits per pixel is the colour depth. This determines the number of possible colours each pixel can be. 1 bit colour = 2 possible colours.
High colour depth = better image quality = larger file size
Size in bits = width x height x colour depth
Size in bytes = size in bits/8
Metadata = Data about data (e.g resolution).
Frequency - Number of waves per second. The wave amplitude is the height of the wave, it controls how loud the sound is.
Sampling - Computer takes snippets of the sound at regular intervals.
Bit depth - Indicates the range of sounds that can be captured. More bits = More original sound.
File size = Sample rate x duration x bit depth
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Character set - A numerical mapping of all the characters available to a computer system. Each character is a binary number.
ASCII is a character set that contains 128 codes - represented in 7 bits.
Unicode - Provides up to 32 bits for characters. ASCII is a subset of Unicode. The numbers are the same for these characters in both unicode and ASCII.
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Bit rate - Binary digits in a sound per second.
Sample frequency - Number of samples per second.
Subroutine - Piece of code that can be reused by a program. You define a subroutine and then you call it. There are two types : Procedure and Function. Function returns a value but Procedure doesn't return any value.
Lossy Compression - Permanently removes data that the human eye cannot notice or hear.
Lossless Compression - Constantly looks for patterns in data to try and reduce the file size. No pattern = larger file size.
ROM - Read only memory - Non volatile meaning data is retained when the computer is turned off.
RAM - Read access memory - Volatile meaning is lost when the computer is turned off.
Cache - Stores frequently accessed data/protocols.
Virtual memory - When RAM is full, the computer looks for programs that haven't been used recently and copies them to Virtual memory on the hard disk.
Secondary Storage - Non volatile so it is used to store data and programs when the power is off.
Magnetic storage - Uses magnetism to store data.
Optical storage - Uses layers to read and write data from a disk.
SSS - Traps electrons in a pattern using flash cell to store data.
WAP - Provides wireless access to a wired network.
Switch - Uses MAC addresses to forward data.
Router - Connects the home network to the internet.
NIC - Connects to a device using cables.
Transmission media - Cabled networks.
Computer network - A set of connected computer and devices needed to share devices/resources.
LAN - Local Area Network - Devices are connected over a small geographical area and infrastructure is normally owned.
WAN - Wide Area Network - Devices are connected over a large geographical area and infrastructure is normally not owned.
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Peer to peer - Computers are networked to each other without a central server and files are stored in individual devices.
Client Server - Relationships between 2 networks in which one is the client which makes the service request from the server.
Domain Name Server - A specific type of server that matches domain names with IP addresses. The domain name is the user friendly name for a website.
Wired - Ethernet Cable carry data using electrical signals.
Wireless - Connect with devices using radio waves.
Encryption - Scrambles data making it impossible to understand if intercepted.
IP address - Internet Protocol
MAC - Media access control
Standards - Provides consistency.
Protocols - Set of rules that determine how networks communicate.