What does the NOT operation do?

It inverts a Boolean value: NOT True is False and NOT False is True. It is used to reverse a condition, for example WHILE NOT found.

What does the AND operation do?

It gives True only when both of its operands are True, and False in every other case. It is used when two conditions must hold at once, for example age >= 13 AND age <= 19.

What does the OR operation do?

It gives True when at least one of its operands is True, and False only when both are False. It is inclusive, so it is still True when both operands are True.

What does the XOR operation do, and how does it differ from OR?

Exclusive OR gives True when exactly one of its operands is True, and False when they are both True or both False. It differs from OR only in the both-True case, which OR calls True and XOR calls False. XOR is the 'one or the other but not both' operator, and it has the useful property that applying the same value twice returns the original.

A is True and B is False. Evaluate NOT A, A AND B, A OR B and A XOR B.

NOT A is False. A AND B is False, because B is not True. A OR B is True, because A is True. A XOR B is True, because exactly one of the two is True.

AQA A-Level Computer Science 7517

Fundamentals of Programming

Topic overview Data types Programming concepts and program structure Arithmetic operations Relational Operations, Constants and Variables Boolean operations String-handling operations Random numbers and exception handling Subroutines, parameters and return values Variable scope and stack frames Recursive techniques Programming paradigms and the procedural approach Classes, Objects, Inheritance and Polymorphism Aggregation, Composition, Class Diagrams and Design Principles

Fundamentals of Data Structures

Topic overview Data Structures and Abstract Data Types Static and Dynamic Data Structures Queues and Linear Queues Circular and Priority Queues Stacks Graphs Trees Hash tables Dictionaries Vectors and Their Notation Vector Arithmetic and Geometry

Fundamentals of Algorithms

Topic overview Graph traversal Tree traversal Reverse Polish notation Searching algorithms Sorting algorithms Optimisation algorithms

Theory of Computation

Topic overview Logic Problems and Algorithm Constructs Pseudo-Code, Hand-Tracing and Program Correctness Representational Abstraction, Generalisation and Information Hiding Procedural and Functional Abstraction Data Abstraction and Problem Reduction Decomposition and Composition Automation and Finite State Machines Sets and Set Notation Subsets and Set Operations Regular expressions and regular languages Backus-Naur Form and syntax diagrams Comparing Algorithms and Functions Order of complexity and Big-O notation Limits of computation, tractability and heuristics Computable problems and the Halting problem Turing machines

Fundamentals of Data Representation

Topic overview Number systems and the sets of numbers Number bases: decimal, binary and hexadecimal Bits, bytes and units of information Unsigned binary and binary arithmetic Signed binary using two's complement Fixed point and floating point representation Normalisation of floating point numbers Rounding errors, accuracy, range and precision Character coding systems Error checking and correction Bit patterns, analogue and digital Bitmapped graphics Vector graphics Digital representation of sound MIDI and Data Compression Encryption

Fundamentals of Computer Systems

Topic overview Hardware, Software and Its Classification System Software and the Operating System Translators and the Role of the Operating System Classification of programming languages Types of program translator Logic Gates and Their Truth Tables Logic Circuits and D-Type Flip-Flops Half-Adders and Full Adders Boolean algebra

Fundamentals of Computer Organisation and Architecture

Topic overview Internal components, buses and von Neumann and Harvard architectures The Stored Program Concept and the Processor The Fetch-Execute cycle The processor instruction set Addressing modes Machine-Code Operations Shifts, Halting and Assembly Language Programs Interrupts Factors affecting processor performance Input and output devices Secondary storage devices

Fundamentals of Communication and Networking

Topic overview Communication methods Communication basics Network Topology and Types of Networking Wireless networking The Internet and Packet Switching Routing, URLs and Domain Names Firewalls, Worms, Trojans and Viruses Encryption, Digital Signatures and Certificates TCP/IP Standard application layer protocols IP Address Structure and Subnet Masking IP Standards and Public and Private Addresses DHCP and Network Address Translation Client server model Thin- versus thick-client computing

Consequences of Uses of Computing

Topic overview The Four Kinds of Issue in Computing Legislation, Ethical Dilemmas and Case Studies

Systematic Approach to Problem Solving

Topic overview Analysis, Design and Implementation Testing and Evaluation

Fundamentals of Databases

Topic overview Conceptual data models and entity relationship modelling Relational databases Database design and normalisation techniques Structured Query Language (SQL)Client server databases

Big Data

Topic overview Volume, Velocity and Variety Why Big Data Resists Analysis Distributed Processing and Functional Programming Fact-Based Models and Graph Schemas

Fundamentals of Functional Programming

Topic overview Function Types, First-Class Objects and Function Application Partial Function Application and Composition Writing functional programs Lists in functional programming

Fundamentals of Programming

Boolean operations

1 thing to know
Paper 1

Overview

Recall questions on the NOT, AND, OR and XOR operations, how XOR differs from OR, evaluating them for given values, and writing compound conditions with them.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Process

Both P and Q are True. Which of P AND Q, P OR Q and P XOR Q are True?

Questions from this subtopic

Each one with the model answer underneath.

1
What does the NOT operation do?
Model answer
It inverts a Boolean value: NOT True is False and NOT False is True. It is used to reverse a condition, for example WHILE NOT found.
2
What does the AND operation do?
Model answer
It gives True only when both of its operands are True, and False in every other case. It is used when two conditions must hold at once, for example age >= 13 AND age <= 19.
3
What does the OR operation do?
Model answer
It gives True when at least one of its operands is True, and False only when both are False. It is inclusive, so it is still True when both operands are True.
4
What does the XOR operation do, and how does it differ from OR?
Model answer
Exclusive OR gives True when exactly one of its operands is True, and False when they are both True or both False. It differs from OR only in the both-True case, which OR calls True and XOR calls False. XOR is the 'one or the other but not both' operator, and it has the useful property that applying the same value twice returns the original.
5
A is True and B is False. Evaluate NOT A, A AND B, A OR B and A XOR B.
Model answer
NOT A is False. A AND B is False, because B is not True. A OR B is True, because A is True. A XOR B is True, because exactly one of the two is True.
6
Both P and Q are True. Which of P AND Q, P OR Q and P XOR Q are True?
Model answer
P AND Q is True and P OR Q is True, but P XOR Q is False, because exclusive OR requires exactly one operand to be True and here both are.

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