Unit 1: Data Representation Flashcards
Convert 2A from hex to denary
16x2+10=42
How do you perform two’s complement in binary?
Reverse all 1s and 0s and then add 1.
Convert denary 14 to hexadecimal.
The scale is 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F, etc.
So therefore the answer is E
What is A32F in binary?
Each hex digit is used for one nibble (four bits)
Therefore A32F = 1010 0011 0010 1111
What is hex F27B in binary?
What is hex ABCD in binary?
What is hex F27B in binary?
1111 0010 0111 1011
What are the advantages of Hex?
It is easier for humans to understand as it is a shorter
representation of the binary
Hex values are also easier to remember and enter
People are less likely to make an error with fewer digits
What is an overflow error?
When the result of an addition is too large for the
number of bits the computer works with, there will be an overflow error
What is the effect of a binary shift to the right?
Division
What is the effect of a binary shift to the left?
Multiplication
What is sample rate in audio files?
Number taken of samples per second(measured in hz)
What is sample resolution?
The number of bits (audio bit depth) used to record
each sample
How do you calculate file size of audio files?(in bits)
File size (bits) = sample rate × resolution × duration
What is image resolution?
Image resolution is the number of pixels in the image
How do you increase the number of colours in an image?
More bits per pixel =
more colour combinations
1 bit = 2 Colours
2 bits = 4 Colours
3 bits = 8 Colours
4 bits = 16 Colours
Bit depth: How many bits per pixel
required for 256 colours?
2^8=256
8 bits per pixel
How do you calculate the file size of an image?
image width x image height x colour depth (in bits)
Describe the effect of reducing the resolution and colour depth of an image.
The file size would be reduced since the there is less data therefore the file would be more compact. The colours would lose their detail and the quality would deteriorate, the same would go for the resolution since you are lowering the amount of pixels in the file.
What is compression?
Compression is reducing the the size of a file so that it takes up less space on secondary storage.
What is the difference between lossy and lossless compression?
Lossy compression permanently loses some data while lossless compression does not lose any data
What is Run Length Encoding?
Run-length encoding (RLE) is a form of data compression that condenses identical elements into a single value with a count
Use RLE to shorten this piece of code assuming 1=white and 0 =black
1111000000000000
Using RLE, the row could be represented as 4 ‘1’s
and 12 ‘0’s or 4 1 12 0
Describe 2 advantages of compression
Smaller files = fewer packets = faster transmission time
Quicker to complete transmission
Reduces traffic over the Internet
Reduces download times of video, sound (including
speech used for VOIP systems) and image files
Streaming is also possible as the data can be sent as fast as the
rate it is played
Images inside web pages appear faster
Reduces space on disk / servers
