Flashcards
Units, Data Storage, Compression
Cards in this deck (29)
- 1Units of Data StorageBit
Nibble
Byte
Kilobyte
Megabyte
Gigabyte
Terabyte
Petabyte - 2Why use binary?CPU is made up of millions of transistors, that can be in one of two states(on/off).
Computers use binary number system to represent data as it's easier to represent just two states for electrical components. - 3Sound File Sizesample rate (Hz) x duration (s) x bit depth
Sample rate x bit depth : "Bit Rate" - 4Image File Sizecolour depth x image height (px) x image width (px)
colour depth : 1 bit = 2 colours, 2 bits = 4 colours, 3 bits = 8 colours
Pixel width and height : the number of pixels in a specific area
No. of pixels used = pixel height x pixel width x bit depth - 5Text File Sizebits per character x number of characters
- 6Denary → BinaryExample:
23
128 64 32 16 8 4 2 1
0 0 0 1 0 1 1 1 - 7Binary Addition0 + 0 = 0
0 + 1 = 1
1 + 1 = 0 carry 1
1 + 1 + 1 = 1 carry 1 - 8Overflow ErrorsOverflow errors happen when the largest number that a register can hold is exceeded. When this happens, the CPU drops the overflow digit as it can't be stored anywhere.
ALWAYS START ADDITIONS ON THE LEFT TO ENSURE OVERFLOW IS CORRECT! - 9Adding Two 8-bit Binary IntegersExample:
0 1 0 1 1 1 1 1
+ 1 1 0 1 1 1 1 0
= 0 0 1 1 1 1 0 1
OF 1 Carry 1 1 1 1 1
OF = Overflow - 10HexadecimalConversion Table:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
0 1 2 3 4 5 6 7 8 9 A B C D E F - 11Denary → HexadecimalExample:
12
0 0 0 0 1 1 0 0
0 C - 12Hexadecimal → DenaryExample:
34
0 0 1 1 0 1 0 0
52 - 13Binary ShiftsSmart and quick way of a computer calculating multiplication and division.
When multiplying in powers of 2, a single left shift occurs.
When dividing in powers of 2, a single right shift occurs. - 14Character SetA character set is a complete set of the characters and their number codes that can be recognised by a computer system.
- 15ASCIIAmerican Standard Code for Information Interchange
7-bit character set
You can represent 128 characters.
A = 01000001 a = 01100001
B = 01000010 b = 01100010
and so on..... - 16Extended ASCII8-bit character set
You can represent 258 characters
Mostly includes special characters! - 17UnicodeAssigned every letter from multiple languages a unique number
Kept ASCII for English language
Too many excess zeros at the start [8 zeros taken as end of string] - 18UTF-8Puts Unicode standard number in 8 bits to remove excess zeros
Puts headers at start of binary to know how many bytes it's dealing with
Can be explained on paper.
Backwards compatible
Never 8 zeros in a row - 19BitmapsImage made up of different coloured squares
Each square has a binary value
Most likely photograph with complex shapes - 20VectorsThe mathematics to store the square are stored:
x and y co-ordinates from the middle
the radius
width
colour
Most likely technical drawings, logos or clipart - 21Bitmap ImagesMade up of PICture Elements or PIXELS
Pixel is smallest identifiable area of an image
Each pixel is a single colour and is given a binary value which represents its colour - 22MetadataData about data
Data other than image data stored in file
Could include:
pixel width and height (resolution)
bit depth (colour depth)
file name
file type
data created
author - 23Effects of Colour Depth and ResolutionIncreasing them increases quality of the image but also the size so it will use up more storage.
Decreasing doesn't use as much storage but the image quality is also poor. - 24Analogue SoundContinually changing data
Computer does not understand these 2signals so they must be converted
USE: Analogue to Digital Converter - 25Digital SoundShown as rigid, instant data
A speaker or headset does not understand digital signals so must be converted
USE: Digital to Analogue Converter - 26Effects of Sample Rate, Duration and Bit DepthHigher bit depth or higher sample rate (Hz) or lengthier duration (s), means the file will increase in quality and size.
- 27CompressionReduces the file size so it takes less space
Maximises the amount you can store on a device
Smaller files are quicker when transferred across the internet - 28Lossy CompressionMake number of of colours smaller or store bigger areas of pixels with one colour
Significantly reduces file size
Both of these reduce quality of image
Works well with full coloured photographs - 29Lossless CompressionDoes not lose any data at all during compression
Don't have to store individual pixels
Eg. store 'white' followed by number of whites needed in a row
Works well with images that have lots of repeating colour
Text documents and executable code MUST be compressed in their entirety without any loss of data
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- GCSE Computing Flashcards on Units, Data Storage, Compression, created by Samndeep _B on 22/02/2021.
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- Samndeep _B
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