CS 1.3 Flashcards
Give 2 reasons why a computer programmer would prefer to write a number in hexadecimal rather than binary.
-Easy to convert to/from binary as 4 bits per hex character.
-more reliable to
communicate
Describe how text is represented in a computer.
Each character has a unique binary value.
The binary of each character is
stored in order.
What is a character set?
It stores all the characters a computer can represent.
Name two character sets. Compare them.
ASCII + Unicode. ASCII is 8 bit so stores 256 characters. Unicode is 16 bit so supports 65,536 characters – this means files are larger but can support more languages.
Describe how an image is represented in a computer.
Images are made of pixels. Each pixel has a binary code that represents the colour. Each colour has a different binary value.
Describe how a sound is represented in a computer.
Sound wave is sampled. Amplitude is measured at set intervals. Sample stored in binary. Samples are stored sequentially.
what is Amplitude
The height of the wave – what is sampled.
what is Bit depth
The number of bits per sample.
what is Sample rate
The frequency of sampling.
what does change in bit depth effect
Bit depth = number of bits per sample. Increasing it will increase the accuracy of each sample but increase the file size.
what does change in Sample rate effet
Sample rate = how frequently the sound is sampled. Increasing increases overall accuracy but increases file size.
what does change in duration of a sound effect
higher duration = higher file size
Give examples of what the metadata of an image can contain.
Colour depth
Resolution
Height / width
Location
Date
what is resolution
Number of pixels in the image. Height * width.
what is colour depth
Number of bits used per pixel, represents the number of different colours that can be used.
what is a pixel
The smallest part of an image. Each pixel has a binary value
describe the need for compression
Compression reduces the size of a file. Makes it faster to send online and uses less space
What is a network?
A network is two or more computing devices connected together to share resources and exchange information
what are the Advantages of networks
Sharing resources
like printers and
files
Centralised
backups and
updates
Easier
communication
between users
what are the disadvantages of networks
Can be expensive
to set up
Security risks if not
properly protected.
Malware can
spread easily.
give characteristics of LAN
Network over a small geographical area
User owns the hardware
give characteristics of WAN
Network over a large geographical area
Uses 3rd party hardware
how does number of users effect network performance
Increased number of users means less bandwidth per user and higher latency leading to lower performance.
how does transmission media effect network performance
Copper slower than fibre-optic.
Wireless is less reliable and slower than wired.
how does latency effect network performance
latency is how much time it takes for a reply to be received. High latency means lower performance.
how does bandwidth effect network performance
bandwidth is how much data can be transferred at once. so higher
bandwidth means higher performance.
how does error rate effect network performance
error rate is Number of errors in the transmission (eg due to wireless
interference). so higher error rate means lower performance.
what is the task performed by the Wireless Access Point
Allows wireless devices to communicate. Sends and receives Wi-Fi.
what is the task performed by the router
Connects networks.
Receives packets.
Forwards packets using IP addresses.
what is the task performed by the switch
Connects devices in a network. Sends data using MAC addresses.
what is the task performed by the NIC
Gives each device a MAC.
Allows computer to connect to network.
what is the task performed by and what is the what is the transition media
Carries data from one device to next.
Connects wired devices to network
Describe what is meant by a server.
A computer that processes requests,
manages clients,
centrally stores files
Identify four types of servers.
Web server
Mail server
File server
Gaming server
Describe what is meant by the cloud.
It is accessing hardware & software that is stored remotely
instead of locally.
advantages of star network
Easy to add a device.
Failed device doesn’t
impact the network.
Fewer cables so cheaper
disadvantages of star network
Reliant on a central switch
Compare two modes of wireless connection.
Wi-Fi & Bluetooth.
Bluetooth shorter range eg for
headphones. Wi-Fi longer range and higher bandwidth.
what is encryption
Scrambling data from plain text to cipher text using a key do it cannot be read
what is a protocol
A set of rules for communication between devices on a network
what is an ip adress
Internet Protocol address – used to identify devices on a WAN.
what is a mac address used for
Used to identify devices on a LAN.
what is HTTP / HTTPS used for
Used to access websites. HTTPS uses encryption so more secure
what is FTP used for
Transferring files from a client to a server.
what is POP used for
Retrieves emails from a mail server.
what is IMAP used for
Retrieves a copy of an e-mail to your computer.
what is SMTP used for
Used to send emails
Describe what is meant by layers.
A division of network functionality.
Explain 2 advantages of using network layers.
- One layer can change without
impacting other layers. - Hardware can be designed for a specific layer.
