Key term
WJEC A-Level Computer Science 601-5345-3
Hardware: Architecture, Memory and Storage
Networks and Data Transmission
Logic Gates and Boolean Algebra
Data Representation and Data Types
Data Structures
Organisation of Data: Files and Records
Database Systems
The Operating System
Algorithms and Programs
Principles of Programming
Systems Analysis
Software Engineering and Program Construction
Topic overviewIntegrated development environments and their purposeEditors, syntax highlighting and code entry toolsDebugging tools: breakpoints, stepping and watchesTranslation, source code and object codeLexical analysis and the symbol tableSyntax and semantic analysisCode generation and optimisation
Types of Software System
Practical Programming
Data Security and Integrity
Computing, Society and the Law
Topic overviewSocial and economic change from computingComputers and the nature of employmentThe digital divide and cultural changeEnvironmental cost of computingData protection and freedom of information lawThe Computer Misuse Act 1990 and computer crimeCopyright, surveillance and professional codes
Advanced Data Structures and Logic
Recursion, Sorting and Searching
Programming Paradigms and Translators
Topic overviewFunctional, declarative and imperative paradigmsClasses, methods and object-oriented designStandardisation of computer languagesAmbiguity in natural language and unambiguous notationBackus-Naur form and syntax diagramsCompilers, interpreters and assemblersTranslation and execution errors
System Design and Human-Computer Interaction
Software Engineering Tools and Professional Practice
Topic overviewSoftware tools for the software engineering processSoftware packages in systems analysis and specificationSoftware packages in systems designTesting tools and testing strategiesProgram version managementProgram libraries and project management toolsCodes of conduct and professional behaviour
Advanced Architecture and Assembly Language
Communication Networks and File Organisation
Number Representation and Floating Point
Databases and Distributed Systems
Topic overviewConsistency, redundancy and data independenceRelational organisation and normalisationRestructuring data into third normal formEntity relationship modellingQuery languages and SQLValidation, verification and the DBMSBig Data, data warehousing and miningDistributed systems and distributed databases
Operating System Management
Software Systems and Applications
Data Security, Cryptography and Attack
Logic Gates and Boolean Algebra
Simplifying Boolean expressions
- 3 things to know
- AS Unit 1
Overview
Recall questions on why simplification is worth doing before a circuit is built, the absorption, complement and distributive laws applied to worked expressions, factorising, and what A ⊕ A, A ⊕ 0 and A ⊕ 1 reduce to.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
Simplify (A + B)·(A + ¬B).
Key term
What does A·¬A + B reduce to?
Questions from this subtopic
Each one with the model answer underneath.
- 1
Why is it worth simplifying a Boolean expression before building the circuit?
Model answer
Fewer gates means a cheaper circuit that draws less power, takes up less space and settles faster because a signal passes through fewer stages.
- 2
Simplify A·B + A.
Model answer
It simplifies to A, by the absorption law.
- 3
Simplify A·(A + B).
Model answer
It simplifies to A, by the second absorption law.
- 4
Simplify (A + B)·(A + ¬B).
Model answer
Using the distributive law it becomes A + B·¬B, and since B·¬B is 0 the result is A.
- 5
What does A·¬A + B reduce to?
Model answer
A·¬A is 0 by the complement law, and 0 + B is B, so the expression is just B.
- 6
Use the absorption law to simplify A + A·¬B.
Model answer
It simplifies to A, because absorption applies whatever the second factor of the AND term happens to be.
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