Key term
Eduqas A-Level Computer Science A500QS
Data Structures: Arrays, Records and Hash Tables
Stacks, Queues, Linked Lists and Trees
Boolean Logic and Simplification
Algorithms, Pseudo-Code and Programming Constructs
Variables, Scope, Parameters and Identifiers
Recursion and Modular Programming
Sorting Algorithms
Searching and Shortest-Path Algorithms
Big O Notation and Algorithm Efficiency
Validation, Verification and Testing
Data Compression
Programming Paradigms and Computer Languages
Topic overviewProgramming paradigms and where each is usedProcedural programmingEvent-driven and visual programmingMark-up languagesObject-oriented programming: objects, classes and methodsAmbiguity in natural language and the standardisation of languagesBackus-Naur form and syntax diagramsHigh-level and low-level languages, and choosing one
Systems Analysis, Maintenance and Documentation
Topic overviewWaterfall, Agile and approaches to systems developmentThe feasibility study, budgets and time scalesMethods of investigationAbstraction, decomposition and data flow diagramsSelecting suitable hardware and softwareAcceptance testing and methods of changeoverPerfective, adaptive and corrective maintenanceBackup and recovery proceduresUser and maintenance documentation
System Design and Human-Computer Interaction
Software Engineering Tools and Translators
Topic overviewSoftware tools for the software engineering processSoftware packages in analysis, specification, design and testingIntegrated development environmentsDebugging toolsProgram version managementCompilers, interpreters and assemblersThe stages of compilationTranslation errors and execution errors
Computing, Society and the Law
Computer Architecture, the Processor and Assembly Language
Topic overviewHardware elements and how they are connectedVon Neumann architecture and the stored program conceptThe processor: control unit, ALU and registersTypes of memory: RAM, ROM and virtual memoryCache memory and locality of referenceThe fetch-execute cycle and its registersParallel processing and the limits to parallelisationAssembly language and executing a program
Input, Output and Secondary Storage
Topic overviewInput devices and how data is capturedOutput devices and how results are presentedChoosing input and output devices for a situationVoice input, dictation and voice print recognitionMagnetic, optical and solid state storageComparing secondary storage for a purposeDisc organisation, fragmentation and defragmentation
Networks, Protocols and the Internet
Topic overviewNetworks, LANs and WANsNetwork topologies and connection hardwareNetworking standards and the layered modelIP addressing, TCP and UDPApplication protocols: HTTP, FTP, SMTP, IMAP and DHCPHandshaking and establishing a connectionWireless hardware and wireless technologiesThe internet and connected mobile devices
Data Transmission and Network Performance
Topic overviewSerial and parallel transmissionSimplex, half duplex and full duplexMultiplexing and sharing a channelCircuit, message and packet switchingPackets, headers and packet contentsNetwork collisions and collision detectionRouting traffic on a networkCalculating transfer rates and lowest cost routes
Number Systems and Binary Arithmetic
Data Types, Characters and Floating Point
Topic overviewPrimitive data typesStorage requirements for each data typeASCII and standardised character setsUnicode and multilingual encodingFloating point form: mantissa and exponentConverting between real numbers and floating pointInteger and floating point comparedTruncation, rounding and accuracy
Files, Records and File Organisation
Topic overviewThe purpose of files in data processingFiles, records and fieldsFixed and variable length fields and recordsMaster files and transaction filesSerial and sequential file accessIndexed sequential access and multi-level indexesDirect access and hashing algorithmsOverflow handling and file reorganisationFile security, backups, generations and archiving
Databases, Normalisation and Entity Modelling
SQL, Big Data and Distributed Systems
Topic overviewQuery languages and the purpose of SQLCreating tables: CREATE TABLE, data types and keysRetrieving data with SELECT, FROM and WHEREComparison operators, IN, AND, OR and sub-queriesSorting, grouping and aggregate functionsInserting, updating, deleting and joining dataThe DBMS, the data dictionary and distributed databasesBig Data, data warehousing, data mining and predictive analytics
The Operating System and Its Modes
Topic overviewThe need for an operating system and the role of the kernelManaging peripherals, processes and memory protectionThe user interface and the layers between user and hardwareDirectory structures and file attributesUtility softwareBatch processing, real time control and real time transaction systemsTypes of operating system: single-user, multi-user, multi-tasking and multi-programmingDesigning an interface for different users and environments
Interrupts, Memory Management and Scheduling
Topic overviewWhat causes an interruptInterrupt handling and the interrupt service routineInterrupt priorities and how they are allocatedPartitioning main memoryMethods of data transfer between processor and devicesBuffers and double bufferingHigh level scheduling, processor and device allocationProcess states, time-slicing, polling and threading
Types of Software System
Data Security, Cryptography and Attack
Topic overviewOnline updating and the integrity of shared filesDangers of holding personal dataClerical procedures, access levels, passwords and write protectionCryptography: its purpose, and symmetric and asymmetric keysHashing, digital signatures and certificatesCaesar and Vernam ciphers and comparing cipher strengthBiometric technologies and their limitationsThreats, damage and contingency planningMalicious software, hacking and penetration testing
Stacks, Queues, Linked Lists and Trees
- 7 subtopics
- 21 things to know
- Component 1
What Stacks, Queues, Linked Lists and Trees covers
Stacks, Queues, Linked Lists and Trees is examined in Component 1, Programming and System Development. It covers stacks: push, pop and the stack pointer, implementing a stack in an array, queues: enqueue, dequeue and pointers, circular queues and priority queues, linked lists: nodes, pointers and the free list, binary trees: nodes, roots and leaves and traversing linked lists and trees.
The 7 subtopics
Each one has its own page.
- Stacks: push, pop and the stack pointerTerm stack pointer, stack overflow and stack underflow.Open →
- Implementing a stack in an arrayHow two stacks can share a single array and operations a stack must provide as an abstract data type.Open →
- Queues: enqueue, dequeue and pointersTwo pointers used with a linear queue, drawback of a simple linear queue held in an array and one way of avoiding wasted space in a linear queue.Open →
- Circular queues and priority queuesCircular queue and priority queue.Open →
- Linked lists: nodes, pointers and the free listLinked list, term node and free list.Open →
- Binary trees: nodes, roots and leavesRoot of a tree, leaf node and binary tree.Open →
- Traversing linked lists and treesTraversal of a linked list, three traversals of a binary tree and in-order traversal.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
What does a dequeue operation do, and which pointers does a linear queue keep?
Key term
How is a stack held in an array?
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What is a circular queue?
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What is a linked list?
Key term
What is a tree?
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What is a traversal?
Key term
What is a stack?
Key term
Write pseudo-code for a push operation on an array-based stack.
Key term
What is a queue?
Key term
How is the next position calculated in a circular queue?
Key term
Define the term node.
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What is the root of a tree?
Key term
Describe the traversal of a linked list.
Key term
What does the push operation do?
Key term
Write pseudo-code for a pop operation on an array-based stack.
Key term
What does the enqueue operation do?
Key term
A circular queue of size 8 has its rear at index 7. State the index used by the next enqueue.
Key term
What is the start pointer of a linked list?
Key term
What is a leaf node?
Key term
Write pseudo-code for the traversal of a linked list.
Take Stacks, Queues, Linked Lists and Trees further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Stack vs Queue
Stack: removing the most recently added item. Queue: removing the one that has waited longest.
Overflow vs Underflow
Overflow: a push onto a full structure. Underflow: a pop or dequeue from an empty one.
Priority queue vs Ordinary queue
Priority queue: serving the most urgent item first. Ordinary queue: serving the earliest arrival.
Questions from this topic
Each one with the model answer underneath.
- 1
What is a stack?
Model answer
A stack is a last in, first out data structure. Items are added and removed at the same end, which is called the top.
- 2
What does the push operation do?
Model answer
A push operation adds a new item to the top of the stack. The stack pointer is increased so that it addresses the new top.
- 3
What does the pop operation do?
Model answer
A pop operation removes and returns the item at the top of the stack. The stack pointer is then decreased by one.
- 4
What does the peek operation do?
Model answer
A peek operation reads the item at the top without removing it. The stack pointer is left unchanged.
- 5
Define the term stack pointer.
Model answer
The stack pointer holds the position of the current top of the stack. Every push and every pop updates the pointer.
- 6
What is stack overflow?
Model answer
Stack overflow occurs when a push is attempted on a stack that is already full. The push must be refused and an error reported.
What is inside Levo
Six ways to work the same material.
Stacks, Queues, Linked Lists and Trees revision questions
- What does Stacks, Queues, Linked Lists and Trees cover in Eduqas A-Level Computer Science?
- 7 subtopics: stacks: push, pop and the stack pointer, implementing a stack in an array, queues: enqueue, dequeue and pointers, circular queues and priority queues, linked lists: nodes, pointers and the free list, binary trees: nodes, roots and leaves and traversing linked lists and trees. Each one has its own page with questions and model answers.
- How is Stacks, Queues, Linked Lists and Trees organised?
- By the Eduqas A500QS specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Stacks, Queues, Linked Lists and Trees, on a schedule.
Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.
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