Source: https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/3-1-6-binary-systems [Revision notes](https://senecalearning.com/en-gb/revision-notes.md) › [KS3](https://senecalearning.com/en-gb/revision-notes/ks3.md) › [Computer Science](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science.md) › [Computer Science: KS3](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3.md) › Binary Systems # Binary Systems Computer Science: KS3, topic 3.1.6 ## Binary Systems Computer systems store and process data as binary digits. ### Why use binary form? ![Why use binary form?](https://image-v2.cdn.app.senecalearning.com/2018-07/31c77d00-497e-4e13-9319-bd43c2c1c731/Computer-Binary-1-0-Byte-.jpg) - Underneath the surface computers are electrical devices that process information by controlling the flow of electricity through billions of wires and transistors (electrical switches) inside the central processing unit and other components. - The presence of electricity represents a 1, and an absence of electricity represents a 0. ### The transistor ![The transistor](https://image-v2.cdn.app.senecalearning.com/2018-08/e6a4bf35-5519-428e-bd17-35c9dac309ca/transistor-electircal-tool-.jpg) - Transistors are electrical components made from semiconductor materials that can act as electrically-controlled switches. - Transistors can be used to temporarily store data, for example in some forms of primary storage (memory). ### Transistors in the CPU ![Transistors in the CPU](https://image-v2.cdn.app.senecalearning.com/2018-07/b43201c6-4785-4a02-8529-99b5ab9f8ea8/Computer-Cache-Memory-CPU-.jpg) - Inside a Central Processing Unit (CPU), transistors are arranged into circuits to perform operations such as calculations when electricity is passed through them. - For example, transistors can be arranged to form an 'adder' circuit that can accept two binary numbers, and output the sum of their values. - Modern CPUs contain over 3 billion transistors, allowing them to perform billions of calculations per second. ## Test yourself on Binary Systems - What represents a 1 in most modern computers? [Practise this topic for free](https://app.senecalearning.com/classroom/course/b89946c5-cfe7-42d6-ae51-9b4631a07589/section/2c7f5e1f-5882-447b-b5fd-572622f671da/session) - Previous topic: [3.1.5 Fetch-Decode-Execute Cycle](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/3-1-5-fetch-decode-execute-cycle.md) - Next topic: [3.1.7 Logic Circuits](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/3-1-7-logic-circuits.md) ## Computer Science: KS3 contents ### 1 Computational Thinking & Algorithms - 1.1 Computational Thinking - [1.1.1 Abstraction Thinking](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/1-1-1-abstraction-thinking.md) - [1.1.2 Decomposition Thinking](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/1-1-2-decomposition-thinking.md) - [1.1.3 Algorithmic Thinking](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/1-1-3-algorithmic-thinking.md) - 1.2 Algorithms - [1.2.1 Algorithms](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/1-2-1-algorithms.md) - [1.2.2 Pseudocode](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/1-2-2-pseudocode.md) - [1.2.3 Flow Diagrams](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/1-2-3-flow-diagrams.md) - [1.2.4 Logical Reasoning & Debugging](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/1-2-4-logical-reasoning-and-debugging.md) - [1.2.5 Reading Algorithms](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/1-2-5-reading-algorithms.md) - [1.2.6 Correcting Algorithms](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/1-2-6-correcting-algorithms.md) - [1.2.7 Complete the Algorithm](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/1-2-7-complete-the-algorithm.md) - [1.2.8 Search Algorithms](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/1-2-8-search-algorithms.md) - [1.2.9 Linear Search](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/1-2-9-linear-search.md) - [1.2.10 Binary Search](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/1-2-10-binary-search.md) - [1.2.11 Sort Algorithms](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/1-2-11-sort-algorithms.md) - [1.2.12 Bubble Sort](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/1-2-12-bubble-sort.md) - [1.2.13 Insertion Sort](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/1-2-13-insertion-sort.md) - [1.2.14 End of Topic Test - Algorithms](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/1-2-14-end-of-topic-test-algorithms.md) ### 2 Programming - 2.1 Programming Fundamentals - [2.1.1 Variables & Constants](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-1-1-variables-and-constants.md) - [2.1.2 Comments](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-1-2-comments.md) - [2.1.3 Input & Output](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-1-3-input-and-output.md) - [2.1.4 Arithmetic Operators](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-1-4-arithmetic-operators.md) - [2.1.5 Relational Operators](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-1-5-relational-operators.md) - [2.1.6 Boolean Operators](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-1-6-boolean-operators.md) - [2.1.7 Sequence](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-1-7-sequence.md) - [2.1.8 Selection](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-1-8-selection.md) - [2.1.9 Iteration](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-1-9-iteration.md) - [2.1.10 Subroutines](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-1-10-subroutines.md) - [2.1.11 Scope](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-1-11-scope.md) - [2.1.12 Data Types](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-1-12-data-types.md) - [2.1.13 Casting](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-1-13-casting.md) - [2.1.14 Arrays](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-1-14-arrays.md) - [2.1.15 2D Arrays](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-1-15-2d-arrays.md) - [2.1.16 Lists](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-1-16-lists.md) - [2.1.17 2D Lists](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-1-17-2d-lists.md) - [2.1.18 Strings](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-1-18-strings.md) - [2.1.19 Syntax Errors](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-1-19-syntax-errors.md) - [2.1.20 Logic Errors](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-1-20-logic-errors.md) - [2.1.21 Runtime Errors](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-1-21-runtime-errors.md) - [2.1.22 End of Topic Test - Programming](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-1-22-end-of-topic-test-programming.md) - 2.2 Designing Code - [2.2.1 Code](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-2-1-code.md) - [2.2.2 Programs](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-2-2-programs.md) - [2.2.3 Writing Your Own Program](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-2-3-writing-your-own-program.md) - [2.2.4 Designing a ‘Basketball’ Game](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-2-4-designing-a-basketball-game.md) - [2.2.5 Turning an Algorithm into an App](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-2-5-turning-an-algorithm-into-an-app.md) - [2.2.6 End of Topic Test - Designing Code](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-2-6-end-of-topic-test-designing-code.md) - 2.3 Python - [2.3.1 Introduction to Python](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-3-1-introduction-to-python.md) - [2.3.2 Input](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-3-2-input.md) - [2.3.3 Output](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-3-3-output.md) - [2.3.4 Casting](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-3-4-casting.md) - [2.3.5 Type Coercion](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-3-5-type-coercion.md) - [2.3.6 Selection](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-3-6-selection.md) - [2.3.7 Iteration](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-3-7-iteration.md) - [2.3.8 Files](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-3-8-files.md) - [2.3.9 File Handling](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-3-9-file-handling.md) - [2.3.10 Identifiers](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-3-10-identifiers.md) - [2.3.11 Whitespace](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-3-11-whitespace.md) - [2.3.12 Comments](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-3-12-comments.md) - [2.3.13 Exceptions](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/2-3-13-exceptions.md) ### 3 Hardware & Software - 3.1 Hardware - [3.1.1 Elements of Computer Systems](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/3-1-1-elements-of-computer-systems.md) - [3.1.2 Central Processing Unit (CPU)](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/3-1-2-central-processing-unit-cpu.md) - [3.1.3 Registers of the Central Processing Unit (CPU)](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/3-1-3-registers-of-the-central-processing-unit-cpu.md) - [3.1.4 Factors Affecting CPU Performance](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/3-1-4-factors-affecting-cpu-performance.md) - [3.1.5 Fetch-Decode-Execute Cycle](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/3-1-5-fetch-decode-execute-cycle.md) - [3.1.6 Binary Systems](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/3-1-6-binary-systems.md) - [3.1.7 Logic Circuits](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/3-1-7-logic-circuits.md) - [3.1.8 Boolean Logic](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/3-1-8-boolean-logic.md) - [3.1.9 End of Topic Test - Logic](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/3-1-9-end-of-topic-test-logic.md) - 3.2 Software - [3.2.1 System Software](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/3-2-1-system-software.md) ### 4 Data - 4.1 Representing Data - [4.1.1 Binary](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/4-1-1-binary.md) - [4.1.2 Converting Binary & Hexadecimal](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/4-1-2-converting-binary-and-hexadecimal.md) - [4.1.3 Converting Denary & Hexadecimal](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/4-1-3-converting-denary-and-hexadecimal.md) - [4.1.4 Binary Arithmetic](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/4-1-4-binary-arithmetic.md) - [4.1.5 Representing Sound](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/4-1-5-representing-sound.md) - [4.1.6 Representing Images](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/4-1-6-representing-images.md) - [4.1.7 Character Sets](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/4-1-7-character-sets.md) - [4.1.8 American Standard Code for Information Interchange](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/4-1-8-american-standard-code-for-information-interchange.md) - [4.1.9 Unicode](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/4-1-9-unicode.md) - [4.1.10 End of Topic Test - Representation](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/4-1-10-end-of-topic-test-representation.md) ### 5 The Internet - 5.1 Networks - [5.1.1 Networks](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/5-1-1-networks.md) - [5.1.2 Geographical Classification of Networks](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/5-1-2-geographical-classification-of-networks.md) - [5.1.3 What is the Internet?](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/5-1-3-what-is-the-internet.md) - [5.1.4 The World Wide Web](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/5-1-4-the-world-wide-web.md) - [5.1.5 Uniform Resource Locators (URLs)](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/5-1-5-uniform-resource-locators-urls.md) - [5.1.6 Web Hosting](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/5-1-6-web-hosting.md) - [5.1.7 HTML](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/5-1-7-html.md) - [5.1.8 Searching the World Wide Web](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/5-1-8-searching-the-world-wide-web.md) - [5.1.9 Good Searching Tips](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/5-1-9-good-searching-tips.md) - [5.1.10 Are You Looking at Reliable Information?](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/5-1-10-are-you-looking-at-reliable-information.md) ### 6 Online Safety & Security - 6.1 Protecting Yourself Online - [6.1.1 Digital Footprints](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/6-1-1-digital-footprints.md) - [6.1.2 Leaving a Safe Online Footprint](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/6-1-2-leaving-a-safe-online-footprint.md) - [6.1.3 Online Safety](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/6-1-3-online-safety.md) - [6.1.4 Malware - Viruses](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/6-1-4-malware-viruses.md) - [6.1.5 Malware](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/6-1-5-malware.md) - [6.1.6 People Online](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/6-1-6-people-online.md) - [6.1.7 Your Feelings](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/6-1-7-your-feelings.md) - [6.1.8 Getting Help](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/6-1-8-getting-help.md) - 6.2 Computing and the Law - [6.2.1 Data Protection Act (1998)](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/6-2-1-data-protection-act-1998.md) - [6.2.2 Computer Misuse Act (1990)](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/6-2-2-computer-misuse-act-1990.md) - [6.2.3 Freedom of Information Act (2000)](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/6-2-3-freedom-of-information-act-2000.md) - [6.2.4 Plagiarism](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/6-2-4-plagiarism.md) - [6.2.5 Copyright](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/6-2-5-copyright.md) - [6.2.6 Copyright Designs and Patents Act (1988)](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/6-2-6-copyright-designs-and-patents-act-1988.md) - [6.2.7 Creative Commons Licensing](https://senecalearning.com/en-gb/revision-notes/ks3/computer-science/computer-science-ks3/6-2-7-creative-commons-licensing.md)