Evaluation
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
Boolean notation and expressions
- 3 things to know
- AS Unit 1
Overview
Recall questions on how AND, OR, NOT and XOR are written, why AND is written like multiplication and where the addition analogy breaks down, operator precedence, evaluating expressions, writing one for an alarm circuit, and why brackets matter.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
How is the OR operation written in Boolean algebra?
Key term
What symbol is conventionally used for XOR?
Questions from this subtopic
Each one with the model answer underneath.
- 1
How is the AND operation written in Boolean algebra?
Model answer
It is written as a dot between the variables, as in A·B, or by writing them next to each other as AB, following the convention of multiplication.
- 2
How is the OR operation written in Boolean algebra?
Model answer
It is written with a plus sign between the variables, as in A + B, following the convention of addition.
- 3
How is the NOT operation written?
Model answer
It is written as a bar drawn over the variable, or in plain text as ¬A, and it means the complement of that value.
- 4
What symbol is conventionally used for XOR?
Model answer
XOR is written with a plus sign inside a circle, as in A ⊕ B.
- 5
Why is AND written like multiplication?
Model answer
Because 0·0, 0·1 and 1·0 all give 0 while 1·1 gives 1, which is exactly what ordinary multiplication of 0 and 1 does.
- 6
Where does the analogy between OR and ordinary addition break down?
Model answer
It breaks down at 1 + 1, which in Boolean algebra is 1 rather than 2, because a Boolean value can only ever be 0 or 1.
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