Computer Science GCES EDEXCEL
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Decomposition And Abstraction Edexcel2 主题
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Algorithms Edexcel11 主题
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Follow And Write Algorithms Edexcel
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Introduction To Programming Concepts Edexcel
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Basic Programming Concepts Edexcel
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Variables Constants And Assignments Edexcel
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Data Structures And Arrays Edexcel
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Arithmetic Relational And Logical Operations Edexcel
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Determine Outputs Of An Algorithm Edexcel
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Types Of Errors Edexcel
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Standard Sorting Algorithms Edexcel
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Standard Searching Algorithms Edexcel
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Algorithm Efficiency Edexcel
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Follow And Write Algorithms Edexcel
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Truth Tables Edexcel3 主题
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Binary Edexcel6 主题
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Data Representation Edexcel4 主题
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Data Storage And Compression Edexcel2 主题
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Hardware Edexcel5 主题
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Software Edexcel3 主题
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Programming Languages Edexcel2 主题
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Networks Edexcel7 主题
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Network Security Edexcel2 主题
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Environmental Issues Edexcel1 主题
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Ethical And Legal Issues Edexcel3 主题
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Cybersecurity Edexcel2 主题
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Develop Code Edexcel6 主题
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Constructs Edexcel4 主题
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Data Types And Data Structures Edexcel5 主题
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Operators Edexcel1 主题
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Subprograms Edexcel2 主题
Limitations Of Binary Edexcel
Exam code:1CP2
Limitations of Binary
What are the limitations of binary?
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Binary representation is constrained by the number of available bits, for example, the number of available bits determines how the following are represented:
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Characters
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Images
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Sound
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The more bits, the greater range of unique values
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The amount of unique values can be calculated with the formula 2number of bits, where 2 is the number base
|
Number of bits |
Expression |
Number of unique values |
|---|---|---|
|
1 |
21 |
2 |
|
2 |
22 |
4 |
|
3 |
23 |
8 |
|
4 |
24 |
16 |
|
5 |
25 |
32 |
|
6 |
26 |
64 |
|
7 |
27 |
128 |
|
8 |
28 |
256 |
Characters
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The number of bits limits the amount of available characters that can be represented
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For example, using 5 bits would allow 32 unique characters to be represented which is not enough to handle the English language (26 x lowercase, 26 uppercase letters etc.)
Images
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Modern computers use a minimum of 24 bits to represent high quality bitmap images
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Three groups of 8 bits are used to represent the amount of red, green & blue in each pixel (RGB)
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24 bits = 16,777,216 unique colours
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Lowering the amount of available bits would reduce the unique colours, reducing the overall quality of the image
Sound
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CD has long been accepted as the standard for music quality, requiring 16 bits to be achieved (216 = 65,536)
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Lowering the amount of available bits, for example in telephone calls reduces the quality of the sound (28 = 256)
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This reduction is most evident in hold music used in telephone calls
Worked Example
State how many bits are needed to represent the 26 capital letters A to Z.
Give a reason for your answer [2]
Number of bits: ………………………………………………….
Reason: …………………………………………………………….
Answer
Number of bits: 5
Reason: 4 bits would allow for 16 which is not enough
OR
5 bits allows for 32 which is enough
Responses