Key term
CCEA AS-Level Digital Technology 2650
Systems Analysis and Development Approaches
Topic overviewThe software crisis and the need for systems developmentUser needs, time and costRoles in a systems development teamThe purpose of analysisFact-finding techniquesFunctional and non-functional requirementsData flow diagramsThe waterfall modelRapid application development and AgileResources, constraints and risks in a software projectProject management, Gantt charts and critical path analysisVersion management
Design, Development and Testing
Topic overviewThe purpose of systems designStoryboarding the user interfacePrototyping the interface and the data modelThe development stage: turning a design into working codeWhy testing runs throughout developmentLevels of testing: unit and integrationSystem testingAcceptance testingAlpha and beta testingThe purpose and components of a test planTypes of test data
Implementation and System Security
Topic overviewThe purpose of system implementationDirect and parallel changeoverPilot and phased changeoverUser documentationTechnical documentationData conversionThe purpose of system maintenanceCorrective, adaptive and perfective maintenanceArchiving dataBackup and recoveryFull, differential and incremental backupsDisaster recovery plans
Programming
Topic overviewThe purpose of a computer programThe integrated development environmentTranslation: compilers, interpreters and assemblersThe stages of compilation and linkingAlgorithms, pseudocode and syntaxVariables, constants and data typesSequence and selectionIteration: count-controlled and condition-controlled loopsFlowcharts and algorithm representationObjects, classes and methodsInheritance and evaluating the object-oriented approach
Data, Information and Data Representation
Topic overviewBits, bytes and units of storageHow many values a given number of bits can holdConverting decimal to binaryConverting binary to decimalTwo's complement and negative numbersCharacter sets: ASCII and UnicodeData, information and knowledgeFactors affecting the quality of informationValidation: range, type, length and presence checksValidation: format checks and lookup checksCheck digits and the Modulus 11 methodBatch totals, verification and the limits of checking
Computer Architecture and Processing Systems
Topic overviewThe processor, the clock and the registersThe fetch-execute cycleBuses, input and output controllers and portsMain memory: RAM, ROM and addressingCache memory and the memory hierarchyFactors that affect processing speedThe need for secondary storageMagnetic, optical and flash storage mediaChoosing secondary storage for common applicationsBatch, real-time and transaction processingAutomatic teller machines and point of sale terminalsSmartphones: input, output and processing
System Software, Application Software and the User Interface
Topic overviewUser interfaces: WIMP, command line and forms dialogueChoosing and evaluating a user interfaceInputting text, sound and videoThe purpose of an operating systemHow an operating system manages memory and processesTypes of operating systemUtility programsThe need for data compression, lossless and lossyZipping and archive filesCommon data file formatsApplication software: generic and special purposeObtaining and delivering software
Web Technology and Multimedia
Topic overviewThe internet, the World Wide Web and web standardsURLs, HTTP and the request-response cycleDomain names, DNS and IP addressesWeb browsers, search engines, cache and cookiesWeb servers, hosting, ISPs and file transferIntranets and how an organisation uses oneCreating web pages with HTMLHTML tags for text, lists, images and linksStyling pages with CSSMultimedia assets in a web pageClient-side and server-side processingSecurity over the internet: encryption, HTTPS and certificates
Programming
- 11 subtopics
- 33 things to know
- AS Unit 1
What Programming covers
Programming is examined in Unit AS 1, Approaches to Systems Development. It covers the purpose of a computer program, the integrated development environment, translation: compilers, interpreters and assemblers, the stages of compilation and linking, algorithms, pseudocode and syntax, variables, constants and data types, sequence and selection, iteration: count-controlled and condition-controlled loops, Flowcharts and algorithm representation, objects, classes and methods and inheritance and evaluating the object-oriented approach.
The 11 subtopics
Each one has its own page. CCEA AS Digital Technology students sit this topic in the first year.
- The purpose of a computer programComputer program, input, process and output model that most programs follow and source code.Open →
- The integrated development environmentIntegrated development environment, purpose of auto-completion in a code editor and what is meant by stepping through code.Open →
- Translation: compilers, interpreters and assemblersTwo advantages of a compiler over an interpreter and two advantages of an interpreter over a compiler.Open →
- The stages of compilation and linkingMain stages a compiler works through, symbol table and syntax error.Open →
- Algorithms, pseudocode and syntaxDry run, term syntax as it applies to a programming language and syntax and the semantics of a statement.Open →
- Variables, constants and data typesTerm variable, declaring a variable and variable and a constant.Open →
- Sequence and selectionSequence in a program, two selection constructs found in most programming languages and condition in a selection statement.Open →
- Iteration: count-controlled and condition-controlled loopsCount-controlled loop, condition-controlled loop and pre-conditioned and a post-conditioned loop.Open →
- Flowcharts and algorithm representationThe standard flowchart symbols for start and stop, process, decision and input or output, how sequence, selection and iteration appear in each, and when a flowchart is clearer than pseudocode.Open →
- Objects, classes and methodsObject in object-oriented programming, class and an object and sending a message to an object.Open →
- Inheritance and evaluating the object-oriented approachMethod overriding, superclass with two sensible subclasses and class hierarchy.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
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What is bytecode, and why is it used?
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Define the term data type.
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What is the danger of relying on global variables?
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What is a count-controlled loop?
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Distinguish between a pre-conditioned and a post-conditioned loop.
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What is an infinite loop, and give one common cause of one.
Evaluation
Give two advantages of using a flowchart to set out an algorithm.
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Explain the is-a test for deciding whether inheritance is appropriate.
Evaluation
Give two advantages of the object-oriented approach.
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Why does the object-oriented approach make maintenance easier?
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Why must every instruction in a program be unambiguous?
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Name four tools you would expect to find in a typical IDE.
Process
Name the main stages a compiler works through.
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What is an algorithm?
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Name the two selection constructs found in most programming languages.
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Distinguish between a class and an object.
Process
Describe the input, process and output model that most programs follow.
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What is the purpose of auto-completion in a code editor?
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What happens during code generation?
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Why must an algorithm come to an end?
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Name four comparison operators used in conditions.
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Which flowchart symbol marks the beginning and the end of an algorithm?
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What is an attribute?
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How can one piece of hardware carry out many completely different jobs?
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What is a breakpoint?
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Why must source code be translated before a computer can run it?
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Why can a compiler never detect a logic error?
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Give three ways an algorithm can be set down before any code is written.
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Define the term variable.
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What is nested selection?
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What does a rectangle represent in a flowchart?
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Define encapsulation.
Take Programming further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Class vs Object
Class: the template a programmer writes once, describing what data and operations exist. Object: a single item built from that template and holding its own values.
Attribute vs Method
Attribute: a data item a software item holds about itself. Method: an operation it can be asked to carry out.
Encapsulation vs Inheritance
Encapsulation: bundling data with the operations on it and hiding the data behind them. Inheritance: passing data items and operations down from a general template to a more specific one.
Questions from this topic
Each one with the model answer underneath.
- 1
What is a computer program?
Model answer
A computer program is an ordered set of instructions, written in a programming language, that a computer carries out in order to perform a task or solve a problem.
- 2
State the main purpose of writing a computer program.
Model answer
The purpose of a computer program is to tell general-purpose hardware exactly what to do, so that a task is carried out automatically, accurately and as often as it is needed.
- 3
Why must every instruction in a program be unambiguous?
Model answer
A processor cannot work out what was intended or choose between two readings, so each instruction must have exactly one possible interpretation or the program will not behave as the programmer expects.
- 4
Describe the input, process and output model that most programs follow.
Model answer
A program takes in data as input, processes that data according to its instructions, and produces output such as a screen display, a printed report or a stored file.
- 5
How can one piece of hardware carry out many completely different jobs?
Model answer
A computer is general-purpose hardware, and loading a different program into memory gives it a different set of instructions, so the same machine can act as a word processor, a games console or a shop till.
- 6
Distinguish between a program and the data it works on.
Model answer
A program is the set of instructions that says what is to be done, whereas data is the collection of values those instructions read, change and produce.
What is inside Levo
Six ways to work the same material.
Programming revision questions
- Is Programming examined at AS in CCEA Digital Technology?
- 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 Programming cover in CCEA AS-Level Digital Technology?
- 11 subtopics: the purpose of a computer program, the integrated development environment, translation: compilers, interpreters and assemblers, the stages of compilation and linking, algorithms, pseudocode and syntax, variables, constants and data types, sequence and selection, iteration: count-controlled and condition-controlled loops, flowcharts and algorithm representation, objects, classes and methods and inheritance and evaluating the object-oriented approach. Each one has its own page with questions and model answers.
- How is Programming organised?
- By the CCEA 2650 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Programming, 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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