Computer Science GCES OCR
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Cpu Architecture Performance And Embedded Systems Ocr5 主题
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Primary And Secondary Storage Ocr6 主题
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Data Storage And Compression Ocr12 主题
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Units Of Data Storage Ocr
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Processing Binary Data Ocr
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Data Capacity And Calculating Capacity Requirements Ocr
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Converting Between Denary And Binary Ocr
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Binary Addition Ocr
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Converting Between Denary And Hexadecimal Ocr
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Converting Between Binary And Hexadecimal Ocr
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Binary Shifts Ocr
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Representing Characters Ocr
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Representing Images Ocr
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Representing Sound Ocr
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Compression Ocr
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Units Of Data Storage Ocr
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Networks And Topologies Ocr6 主题
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Wired And Wireless Networks Protocols And Layers Ocr6 主题
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Identifying And Preventing Threats To Computer Systems And Networks Ocr2 主题
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Operating Systems And Utility Software Ocr2 主题
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Ethical Legal Cultural And Environmental Impact Ocr2 主题
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Computational Thinking Searching And Sorting Algorithms Ocr3 主题
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Designing Creating And Refining Algorithms Ocr5 主题
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Programming Fundamentals And Data Types Ocr5 主题
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Additional Programming Techniques Ocr7 主题
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Defensive Design And Testing Ocr6 主题
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Boolean Logic Diagrams Ocr2 主题
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Programming Languages And Integrated Development Environments Ides Ocr3 主题
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The Exam Papers Ocr2 主题
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Structuring Your Responses Ocr3 主题
Converting Between Denary And Binary Ocr
Exam code:J277
Denary to Binary Conversion
What is denary?
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Denary is a number system that is made up of 10 digits (0-9)
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Denary is referred to as a Base-10 number system
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Each digit has a weight factor of 10 raised to a power, the rightmost digit is 1s (100), the next digit to the left 10s (101) and so on
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Humans use the denary system for counting, measuring and performing maths calculations
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Using combinations of the 10 digits we can represent any number

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In this example, (3 x 1000) + (2 x 100) + (6 x 10) + (8 x 1) = 3268
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To represent bigger number we add more digits
What is binary?
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Binary is a number system that is made up of two digits (1 and 0)
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Binary is referred to as a Base-2 number system
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Each digit has a weight factor of 2 raised to a power, the rightmost digit is 1s (20), the next digit to the left 2s (21) and so on
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Using combinations of the 2 digits we can represent any number

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In this example, (1 x 8) + (1 x 4) = 12
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To represent bigger numbers we add more binary digits (bits)
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128 |
64 |
32 |
16 |
8 |
4 |
2 |
1 |
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27 |
26 |
25 |
24 |
23 |
22 |
21 |
20 |
Why do computers use binary?
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The CPU is made up of billions of tiny transistors, transistors can only be in a state of on or off
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Computers use binary numbers to represent data (1 = on, 0 = off)
Examiner Tips and Tricks
Don’t forget to show your working! Data conversion questions will often be worth 2 marks, 1 for the answer and 1 for your working
Denary to binary conversion
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It is important to know the process of converting from denary to binary to understand how computers interpret and process data
Example 1
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To convert the denary number 45 to binary, start by writing out the binary headings from right to left
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Start at the leftmost empty column heading (128). Is the denary number > column heading? (45 > 128) No, put a 0 in the 128 column. Repeat until you put a 1 under a heading. In this example it would be 32
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128 |
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32 |
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0 |
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Next subtract column heading from denary value, 45-32 = 13
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Repeat previous two steps until you have a value under each column heading
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128 |
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32 |
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32 + 8 + 4 + 1 = 45
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Denary 45 is 00101101 in Binary
Examiner Tips and Tricks
At GCSE you will only be asked to convert from/to binary up to and including 8 binary digits (8 bits). That means you are working with a denary range of 0-255 (00000000-11111111)
Example 2
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To convert the denary number 213 to binary, start by writing out the binary headings from right to left
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Start at the leftmost empty column heading (128). Is denary number > column heading? (213 > 128) Yes, put a 1 under the heading.
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128 |
64 |
32 |
16 |
8 |
4 |
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1 |
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1 |
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Responses