What is systems software?

Systems software is the layer of programs that runs and manages the computer itself, providing services such as file handling, memory management and hardware control to every other program.

What is application software?

Application software is a program written to do a job for the user, such as editing a document, booking a ticket or keeping a set of accounts.

Why is systems software described as sitting between the hardware and the application?

Systems software owns the hardware and hands out controlled access to it, so an application asks the operating system for a service instead of driving the device itself.

What two services does systems software provide that an application would otherwise have to build for itself?

Systems software provides file storage and retrieval, and it provides memory allocation; an application also relies on it for scheduling processor time and for talking to devices.

Why does an application programmer not write code to position the read head on a disk?

Disk positioning is handled by the operating system and its device drivers, so every application shares one tested implementation and no application needs to know which make of drive is fitted.

CCEA A-Level Software Systems Development CL4

Software and the Development Environment

Topic overview Systems software and application software The operating system and file management Source code files Binary, object and executable files Compilers, interpreters and the build process XML files and structured data Utility software and managing files on disk The integrated development environment Object oriented development platforms Open source software and licensing

Defining Data: Types, Variables and Classes

Topic overview Primitive types and their storage Reference types, objects and null Declaring variables, scope and lifetime Type casting and conversion Arithmetic operators and expressions Relational and logical operators Operator precedence and evaluation order Objects as occurrences of a class Abstract, base and inherited classes Attributes and the properties of a class Static variables in a class Interfaces and class reusability

Program Control Structures

Topic overview Sequence and the order of execution Methods and passing control between them Selection with IF and IF ELSE Nested IF and multi-way selection The switch statement Count-controlled repetition with FOR Conditional repetition with WHILE and DO WHILE Nested loops and tracing iterations Breaking out of loops and avoiding infinite loops Choosing and evaluating control structures

Objects, Classes and Data Structures

Topic overview Constructors and creating objects Methods, parameters and return values Encapsulation and access modifiers Getters, setters and validating an object's state Inheritance and the base class Overriding methods and run-time polymorphism Overloading methods Choosing and organising data structures Strings and string handling Static arrays of simple types Arrays of objects

Exception Handling and Managing Input and Output

Topic overview Why errors have to be trapped Types of error and how an exception is raised The try and catch block Catching more than one kind of exception The finally block and releasing resources Throwing exceptions and writing an exception class Checked and unchecked exceptions Reading and validating input from the command line Controlling screen output Text files Binary files Object files and serialisation

Testing an Object Oriented Application

Topic overview Why an object oriented application must be tested Choosing test data: normal, boundary and erroneous Writing a test plan for a class Testing a class method by method Testing constructors and object state Testing inheritance and overridden methods Testing error handling paths Dry runs and trace tables Test harnesses, drivers and stubs Recording and interpreting test results Evaluating a test plan and re-testing

Graphical User Interface Objects and Events

Topic overview Graphical user interfaces and console programs Forms and their common properties Labels, text boxes and text areas Buttons, check boxes and radio buttons Lists, combo boxes and other selection controls Properties, methods and events of a GUI object Containers, panels and laying out a form The event loop and the event queue Event handlers and registering a listener The event object and reading it inside a handler Button, mouse and keyboard triggers

Multiple Forms and Linking to Files

Topic overview Why an application needs more than one form Creating, showing, hiding and closing a form Modal and modeless forms Passing data between forms Menus, menu items and shortcuts Toolbars and navigation buttons Designing navigation for a multi form application Reading and writing text files Binary files and streams Object serialisation and object files Choosing between text, binary and object files

Designing, Testing and Evaluating an Event Driven Application

Topic overview Storyboards and what they show Building a storyboard from user requirements Prototyping and refining a design Error trapping in an event driven application Using try and catch inside an event handler Validating what a user types into a control Designing a test strategy for an event driven application Test plans and choosing test data Testing the paths a user takes through an interface Documenting and interpreting test results Evaluating an application against its requirements Evaluating features, functionality and usability

Reasons for Systems Development and Systems Methodologies

Topic overview Why organisations initiate systems development Analysis and design principles for business solutions Roles in development and the place of the user The purpose of a methodology and how methodologies evolved The waterfall model Iterative, incremental and spiral development Rapid application development The dynamic systems development method Scrum Extreme programming Prototyping in the development process UML modelling and simple diagrams

Managing Projects

Topic overview The purpose of project management Project management concepts and the project life cycle Roles and responsibilities in project management Resources needed to develop a project Estimating effort, duration and cost Gantt charts and the schedule Milestones and checkpoints Network diagrams and PERT Finding the critical path Float and how it is used Monitoring and controlling progress Managing risk and change

Testing Strategies

Topic overview Why testing matters throughout the development cycle Testing at the design stage Program and unit testing Integration testing System testing White box testing Black box testing Normal, boundary and erroneous test data User acceptance, alpha and beta testing The personnel involved in testing What a test plan contains Building a test plan for a scenario

Database Concepts and Entity Relationship Modelling

Topic overview What a database is and why one is used Database terminology: fields, records and keys The relational model The hierarchical model The network model Entities and attributes in an ER model Relationships and their degree Building an ER model for a problem From ER model to a working design Comparing the three database models

Normalisation and Structured Query Language

Topic overview Why data is normalised Un-normalised data and repeating groups First normal form Second normal form Third normal form Working a full normalisation through The advantages and limits of normalisation The principles of SQL SQL commands for defining and changing data SQL statements for retrieving data Joining tables and grouping results

Project Management and the Systems Approach in Practice

Topic overview Breaking a development into tasks and deliverables Estimating durations, effort and dependencies Documenting the plan as a Gantt chart Working out the critical path and float Milestones, reviews and user sign-off points Planning people, resources and skills Building a plan capable of reflecting change Recording progress against the plan Updating the plan to reflect slippage Recording change requests and versions of the plan Evaluating different approaches to a business problem Selecting and justifying a specific approach

Defining Requirements and Documenting the Design

Topic overview Eliciting requirements from the user Writing functional requirements Writing non-functional requirements Specifying the software and hardware the solution needs Producing and agreeing the user requirements specification Designing the data model and the tables Designing the inputs, the screens and the navigation Designing the outputs and the reports Documenting the processes and the logic of the solution Testing the design against the desired user outcomes Presenting the design and the solution using appropriate media

Building a Desktop Solution with a Database

Topic overview Applying relational techniques to a real solution Choosing the database and the development tool Connecting the application to the database Data adaptors Data sets Data commands and parameterised queries Binding the database to the interface Multiple forms and navigation Saving changes and protecting the data Testing and documenting the built solution

Testing and Evaluating the Solution

Topic overview Planning the testing of the finished solution Choosing test data: normal, boundary and erroneous Testing validation and error handling Testing the database and its queries Testing the user interface and the navigation Testing the whole solution and testing with the user Documenting test outcomes as evidence Diagnosing failures and retesting Evaluating the test procedures Evaluating the solution against the user requirements Evaluating delivery against the project plan Evaluating your own performance on the development

Software and the Development Environment

10 subtopics
30 things to know
AS Unit 1

What Software and the Development Environment covers

Software and the Development Environment is examined in Unit AS 1, Introduction to Object Oriented Development — a written examination. It covers systems software and application software, the operating system and file management, source code files, binary, object and executable files, compilers, interpreters and the build process, XML files and structured data, utility software and managing files on disk, the integrated development environment, object oriented development platforms and open source software and licensing.

Where it is assessed

AS Unit 1

Introduction to Object Oriented Development.

Check the CCEA specification ↗

The 10 subtopics

Each one has its own page.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

Who is systems software written for, and who is application software written for?

Process

Explain why fitting a new printer usually needs new systems software but no change to a word processor.

Key term

Why does renaming a text file so that it ends in .exe not make the file runnable?

Key term

What are three items of metadata an operating system typically records about a file?

Key term

Explain why the operating system, rather than each application, controls access to the disk.

Process

Why can source code not be run directly by the processor?

Key term

Why is source code portable between machines when an executable often is not?

Key term

Why does a binary file appear as nonsense in a text editor?

Key term

What is a library file, and how does a library differ from an executable?

Process

State, in order, the stages that turn several source files into a running program.

Key term

How does a virtual machine allow one compiled program to run on several operating systems?

Key term

What are four rules an XML document must obey to be well-formed?

Key term

How does a defragmenter improve read performance on a mechanical hard disk?

Key term

Why does an IDE keep a project file?

Key term

What are three criteria for evaluating an object oriented platform before starting a new project?

Key term

Explain why a widely adopted platform tends to be more dependable than a niche one.

Key term

What is the essential difference between open source and proprietary software?

Key term

What does XML stand for, and what is XML used for?

Key term

What are four utility programs found on a typical development machine?

Key term

What are four facilities a typical IDE provides?

Key term

Is open source software always free of charge? Explain the answer.

Key term

What are three categories of systems software?

Key term

In what format is a source file stored, and why does that format matter?

Key term

What is a binary file?

Key term

What does an interpreter do?

Key term

Why is XML described as self-describing?

Key term

What does a file compression utility do?

Key term

What is syntax highlighting, and how does it help a programmer?

Key term

What is a class library?

Evaluation

What are three advantages of building on an open source platform?

Take Software and the Development Environment further

The same content, four other ways.

Commonly confused

Pairs that lose marks when they are blurred together.

Well-formed XML vs Valid XML
Well-formed XML: markup that obeys the syntax rules of the language and no more. Valid XML: markup that also matches a declared definition of which elements may appear and where.

Questions from this topic

Each one with the model answer underneath.

1
What is systems software?
Model answer
Systems software is the layer of programs that runs and manages the computer itself, providing services such as file handling, memory management and hardware control to every other program.
2
What is application software?
Model answer
Application software is a program written to do a job for the user, such as editing a document, booking a ticket or keeping a set of accounts.
3
What are three categories of systems software?
Model answer
Operating systems, utility programs and development software such as compilers, linkers and debuggers are all systems software.
4
Why is systems software described as sitting between the hardware and the application?
Model answer
Systems software owns the hardware and hands out controlled access to it, so an application asks the operating system for a service instead of driving the device itself.
5
What two services does systems software provide that an application would otherwise have to build for itself?
Model answer
Systems software provides file storage and retrieval, and it provides memory allocation; an application also relies on it for scheduling processor time and for talking to devices.
6
Why does an application programmer not write code to position the read head on a disk?
Model answer
Disk positioning is handled by the operating system and its device drivers, so every application shares one tested implementation and no application needs to know which make of drive is fitted.

See the rest and revise

What is inside Levo

Six ways to work the same material.

1Closed book

2Open book

3Closed book

The 3-step method, run for you

Answer cold, learn it, then prove it stuck. Levo tracks the jump between your first attempt and your last.

Software and the Development Environment

Defining Data: Types, Variables and Classes

Program Control Structures

Objects, Classes and Data Structures

Cram a whole paper in one sitting

Sort every topic into what you know and what you do not, then drill only the weak ones.

A null is the of one.

absencepresencetype

Blank Blitz makes facts automatic

Rapid timed gap-fills on the terms and numbers you need to recall without thinking.

AA null means no value has been recorded.

BZero and an empty string are values.

CA null is the absence of a value.

Build It gets the exam shape right

Assemble a full-mark answer from its marking points, in the order an examiner wants them.

An error is the mistake a person made.

TrueFalse

Test It catches misconceptions

Spot the fault in a statement. The traps are the mistakes students actually make.

721941163128510

Brain Breaks between sessions

Short focus games to reset attention, so the next set lands better than the last.

Software and the Development Environment revision questions

What does Software and the Development Environment cover in CCEA A-Level Software Systems Development?: 10 subtopics: systems software and application software, the operating system and file management, source code files, binary, object and executable files, compilers, interpreters and the build process, xml files and structured data, utility software and managing files on disk, the integrated development environment, object oriented development platforms and open source software and licensing. Each one has its own page with questions and model answers.
How is Software and the Development Environment organised?: By the CCEA CL4 specification, subtopic by subtopic, so it matches the order you are taught it in.

Every question in Software and the Development Environment, 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.

Start revising, £5 a month See how the method works

Or £46 a year, about £3.83 a month. Cancel anytime.