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.