Why is pseudocode described as independent of any language?

Pseudocode uses code-like keywords, variables and assignment without the exact syntax rules of any one language, so a programmer working in any language can read it and implement it.

Give two advantages of writing an algorithm in pseudocode rather than in a programming language.

It can be understood by anyone regardless of the language they program in, and the logic can be corrected without worrying about syntax errors.

What is structured English?

Structured English describes an algorithm in restricted, numbered English sentences that use a small set of keywords such as IF, REPEAT and UNTIL.

WJEC AS-Level Computer Science 601-5345-3

Hardware: Architecture, Memory and Storage

Topic overview Components of a computer system and how they connect Von Neumann architecture and the CPU The fetch-execute cycle Memory and caching Parallel processing Input and output devices and their uses Secondary storage, fragmentation and defragmentation

Networks and Data Transmission

Topic overview Serial and parallel transmission Simplex, half duplex and full duplex Multiplexing and switching Packets and the TCP/IP protocol stack Networks, standards and protocols Collisions and shared media Routing, addressing and the internet

Logic Gates and Boolean Algebra

Topic overview Logic gates and their truth tables Boolean notation and expressions Building and reading truth tables Boolean identities and rules Simplifying Boolean expressions De Morgan's laws Masking and clearing registers

Data Representation and Data Types

Topic overview Bits, bytes and words The binary number system Hexadecimal notation Character sets and storing characters Primitive data types and storage requirements Binary arithmetic and negative numbers Real numbers, truncation and rounding

Data Structures

Topic overview Data structures and data types One-dimensional arrays Two-dimensional arrays Manipulating arrays Records and fields Arrays of records Choosing a data structure

Organisation of Data: Files and Records

Topic overview Files, records and fields Fixed and variable length records Master and transaction files File access and organisation methods Sequential file access and update algorithms File security, backup and archiving Data validation and verification

Database Systems

Topic overview Flat files and the relational model Relational and other contemporary database systems Primary, foreign, composite and candidate keys Indexes and links between tables Entity relationship modelling Normalisation to third normal form The database management system, queries and user views

The Operating System

Topic overview The need for an operating system The kernel and process management Memory protection and the backing store The user interface between user and hardware Directory structures and file attributes Utility software Batch, real time control and transaction processing

Algorithms and Programs

Topic overview Defining and designing algorithms Variables, constants and identifiers Scope, subprograms and parameter passing Sequence, selection and repetition Mathematical and logical operations Standard algorithms: sorting, searching and compression Dry running, trace tables and test data

Principles of Programming

Topic overview Procedural programming Event-driven and visual programming Mark-up languages Object-oriented programming: objects, classes and methods High-level languages Low-level languages Choosing a language for a problem

Systems Analysis

Topic overview The systems life cycle and the feasibility study Methods of investigation Analysis, abstraction and decomposition Design and data flow diagrams Testing and changeover Maintenance Backup, recovery and documentation

Software Engineering and Program Construction

Topic overview Integrated development environments and their purpose Editors, syntax highlighting and code entry tools Debugging tools: breakpoints, stepping and watches Translation, source code and object code Lexical analysis and the symbol table Syntax and semantic analysis Code generation and optimisation

Types of Software System

Topic overview Off-the-shelf, bespoke and custom software Open source and proprietary software Computers in weather forecasting Computer aided design and manufacture Robotics in industry Computer generated graphics and animation Expert systems

Practical Programming

Topic overview Designing data structures: fields, records and data types Key fields and methods of access Validation of input data Designing routines with pseudocode Tracing code and test data Prototyping and evaluating a solution Annotated listings and readable code

Data Security and Integrity

Topic overview Dangers of holding files of personal data Levels of permitted access and access control Passwords and authentication Clerical procedures and write-protection Threats to computer systems Malicious and accidental damage to data Contingency planning and disaster recovery

Computing, Society and the Law

Topic overview Social and economic change from computing Computers and the nature of employment The digital divide and cultural change Environmental cost of computing Data protection and freedom of information law The Computer Misuse Act 1990 and computer crime Copyright, surveillance and professional codes

Algorithms and Programs

7 subtopics
21 things to know
AS Unit 1

What Algorithms and Programs covers

Algorithms and Programs is examined in AS Unit 1, Fundamentals of Computer Science. It covers defining and designing algorithms, variables, constants and identifiers, scope, subprograms and parameter passing, sequence, selection and repetition, mathematical and logical operations, standard algorithms: sorting, searching and compression and dry running, trace tables and test data.

Where it is assessed

AS Unit 1

Fundamentals of Computer Science, examined again at A2 at a more demanding level.

Check the WJEC specification ↗

The 7 subtopics

Each one has its own page. WJEC AS Computer Science students sit this topic in the first year.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

Write an algorithm in pseudocode that reads numbers until −1 is entered and then outputs their total.

Key term

Explain why the order of operations matters, using an example.

Key term

Why can a dry run reveal a logic error that simply running the program does not?

Key term

What is an algorithm?

Key term

What is a variable?

Key term

What is a local variable?

Key term

State the number of comparisons made by the first pass of a bubble sort on a list of 10 items.

Key term

State two properties every algorithm must have.

Key term

What is a constant?

Key term

What is a global variable?

Process

What is meant by sequence in an algorithm?

Key term

Name four arithmetic operations used in algorithms.

Key term

Describe how a linear search finds a value.

Key term

What is a trace table, and what does each column hold?

Key term

Name three ways of defining an algorithm.

Key term

Give two reasons for declaring a constant instead of typing the value wherever it is needed.

Key term

What is meant by the lifetime of a variable?

Key term

Which pseudocode statement carries out selection?

Key term

What does the DIV operator return?

Key term

State what must be true of a list before a binary search can be used on it.

Key term

Name the three kinds of test data.

Take Algorithms and Programs further

The same content, four other ways.

Questions from this topic

Each one with the model answer underneath.

1
What is an algorithm?
Model answer
An algorithm is a finite sequence of precise, unambiguous steps that solves a problem or completes a task.
2
State two properties every algorithm must have.
Model answer
Every step must be unambiguous, and the sequence must finish after a finite number of steps rather than running for ever.
3
Name three ways of defining an algorithm.
Model answer
Pseudocode, a flowchart and structured English are three ways.
4
Why is pseudocode described as independent of any language?
Model answer
Pseudocode uses code-like keywords, variables and assignment without the exact syntax rules of any one language, so a programmer working in any language can read it and implement it.
5
Give two advantages of writing an algorithm in pseudocode rather than in a programming language.
Model answer
It can be understood by anyone regardless of the language they program in, and the logic can be corrected without worrying about syntax errors.
6
What is structured English?
Model answer
Structured English describes an algorithm in restricted, numbered English sentences that use a small set of keywords such as IF, REPEAT and UNTIL.

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Hardware: Architecture, Memory and Storage

Networks and Data Transmission

Logic Gates and Boolean Algebra

Data Representation and Data Types

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Algorithms and Programs revision questions

Is Algorithms and Programs examined at AS in WJEC Computer Science?: Yes. It sits in AS Unit 1, which you take in the first year, so it is on the AS paper as well as counting towards the full A level.
What does Algorithms and Programs cover in WJEC AS-Level Computer Science?: 7 subtopics: defining and designing algorithms, variables, constants and identifiers, scope, subprograms and parameter passing, sequence, selection and repetition, mathematical and logical operations, standard algorithms: sorting, searching and compression and dry running, trace tables and test data. Each one has its own page with questions and model answers.
How is Algorithms and Programs organised?: By the WJEC 601-5345-3 specification, subtopic by subtopic, so it matches the order you are taught it in.

Every question in Algorithms and Programs, on a schedule.

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