Know and understand applications software provides the services that the user requires to solve a task

ICT 0417 – Types and Components of Computer Systems

Learning Objective

Know and understand how application software provides the services that the user requires to solve a task.

1. Computer System Overview

A computer system is built from three inter‑related layers:

1. Hardware – physical components that perform processing, storage and I/O.
2. System software – manages the hardware and provides a platform for applications (operating system, utility software).
3. Application software – programs that enable users to carry out specific tasks (word processing, spreadsheets, databases, graphics, web‑authoring, etc.).

1.1 Advantages of the Layered Model

• Separation of concerns – hardware can be upgraded without changing software.
• Portability – the same application can run on different hardware if a compatible OS is present.
• Security – system software can control access to hardware resources.

2. Hardware – Main Internal Components

2.1 Internal vs. Backing (Secondary) Storage

• Internal (primary) storage: RAM and ROM – fast, directly accessed by the CPU.
• Backing storage (retains data when power is removed):

  • Magnetic – Hard‑disk drives (HDD), magnetic tape.
  • Optical – CD, DVD, Blu‑ray.
  • Solid‑state – SSD, USB flash drives, memory cards.

2.2 Advantages / Disadvantages of Storage Types

3. System Software – Operating Systems (OS)

The OS controls hardware, manages files, provides security and offers a user interface.

3.1 Types of OS Interfaces

3.2 OS Functions (Key Services)

• File management – create, edit, copy, move, delete files and folders.
• Memory management – allocate RAM to running programmes.
• Process management – start, pause, stop applications.
• Device control – drivers enable communication with printers, scanners, etc.
• Security – user accounts, permissions, authentication, firewalls.
• Network services – TCP/IP stack, Wi‑Fi management.

4. Types of Computers (by Form‑Factor)

5. Input and Output (I/O) Devices

5.1 Input Devices – Characteristics

• Keyboard – alphanumeric entry; includes numeric keypad.
• Mouse / Touch‑pad / Trackball – point‑and‑click navigation.
• Touch screen – direct interaction; combines input & output.
• Scanner – converts paper documents or images into digital files.
• Digital camera / Webcam – captures still images or video.
• Microphone – records audio.
• Joystick, game controller, steering wheel – specialised for gaming or simulation.
• Barcode / QR‑code scanner – reads encoded data for inventory, ticketing.
• Magnetic stripe & RFID readers – used in payment terminals, access control.
• OMR / OCR devices – recognise marks or printed characters for data entry.
• Sensor devices – temperature, motion, GPS, etc., for specialised applications.

5.2 Output Devices – Characteristics

• Monitor / LCD / LED – visual display of information.
• Printer – produces hard copies; ink‑jet, laser, dot‑matrix.
• Speakers / Headphones – audio output.
• Projector – enlarges visual output for presentations.
• Plotter – prints large‑scale vector graphics (architectural plans).
• Haptic devices – provide tactile feedback (vibration, force‑feedback).

5.3 Advantages / Disadvantages of I/O Devices

6. Networks and Communication

6.1 Network Hardware

• Router – forwards data between different networks (e.g., home LAN to the Internet).
• Switch – connects multiple devices within the same LAN, directing traffic efficiently.
• Hub – repeats incoming signals to all ports (now largely obsolete).
• Access point – provides Wi‑Fi connectivity for wireless devices.
• Modem – converts digital data to analogue signals for transmission over telephone or cable lines.
• NIC (Network Interface Card) – wired (Ethernet) or wireless (Wi‑Fi) adapter.
• Bluetooth adapter – short‑range wireless communication.

6.2 Types of Networks (with Advantages & Disadvantages)

6.3 Network Security & E‑Safety

• Physical security – lock rooms, cable management, UPS, surge protectors.
• Password hygiene – strong, unique passwords; regular changes; use of pass‑phrases.
• Two‑factor authentication (2FA) – adds a second verification step.
• Firewalls – hardware or software that filters incoming/outgoing traffic.
• Encryption – HTTPS, VPNs, file encryption for data in transit and at rest.
• Anti‑malware/antivirus – scans and removes malicious software.
• Safe browsing practices – avoid phishing emails, suspicious links, and untrusted downloads.
• Backup & recovery – regular backups (local & cloud), test restores.

6.4 Data Protection & Threats to Data

• Data protection legislation – GDPR, Data Protection Act – requires lawful processing, consent, and right to access.
• Common threats:

  • Malware (viruses, ransomware, spyware)
  • Phishing & social engineering
  • Unauthorised access (hacking, insider threats)
  • Data loss (hardware failure, accidental deletion)
  • Data leakage (unprotected Wi‑Fi, insecure cloud storage)

• Mitigation strategies – regular updates, strong authentication, encryption, user education, least‑privilege principle.

7. Application Software – Categories & Services

8. Using Application Software Effectively

8.1 Audience & Copyright

• Identify the intended audience (e.g., teachers, customers, management) to choose appropriate tone, layout and level of detail.
• Respect copyright – use only licensed or royalty‑free images, fonts, and content; give proper attribution.

8.2 File Management

• Folder hierarchy – create logical folders (e.g., Reports/2025/January).
• File naming conventions – use descriptive names, avoid spaces, include version numbers (e.g., ExpenseReport_V2.docx).
• File formats – choose appropriate format:

  • DOC/DOCX – editable word processing.
  • PDF – fixed layout for distribution.
  • XLSX – spreadsheet data.
  • CSV – plain‑text data exchange.
  • JPG/PNG – images (lossy vs lossless).

• Compression – ZIP files for sending multiple documents.

8.3 Styles & Formatting

• Use built‑in styles (Heading 1, Normal, Title) for consistent formatting and easy updating.
• Apply templates for repeated documents (letters, invoices).
• Set margins, line spacing, alignment to meet organisational standards.
• Use headers/footers for page numbers, document title, date.

8.4 Proof‑reading & Validation

• Spell‑check and grammar tools – catch typographical errors.
• Auto‑correct and custom dictionaries – improve accuracy for specialised terminology.
• Data validation in spreadsheets – restrict input types (e.g., whole numbers, dates) to reduce errors.
• Review graphics for resolution (300 dpi for print, 72 dpi for web).

8.5 Security Measures for Files

• Password‑protect sensitive documents.
• Encrypt files before sending via email.
• Set appropriate file permissions on shared drives.

9. Document Production – Key Software Features

9.1 Word Processing

• Templates, styles, mail‑merge, track changes, comments.
• Insert tables, images, hyperlinks, cross‑references.
• Print layout view – page breaks, headers/footers, page numbers.

9.2 Spreadsheets

• Formulas (e.g., =SUM(A1:A10)), built‑in functions (AVERAGE, VLOOKUP, IF).
• Charts – bar, line, pie, scatter.
• Conditional formatting – highlight cells that meet criteria.
• Data sorting & filtering.

9.3 Databases

• Tables with fields (columns) and records (rows).
• Primary key – uniquely identifies each record.
• Foreign key – links tables together.
• Queries – retrieve specific data (e.g., SELECT * FROM Students WHERE Grade='A').
• Forms for data entry; reports for printing.

9.4 Presentation Software

• Slide master – consistent layout across all slides.
• Animations & transitions – enhance flow, but use sparingly.
• Embed multimedia – video, audio, hyperlinks.
• Presenter view – notes, timer, preview of next slide.

9.5 Graphics / CAD

• Raster vs vector graphics – PNG/JPG (raster) vs SVG/EPS (vector).
• Layers – organise elements.
• Tools – selection, drawing, colour fill, gradients.
• Export options – print‑ready PDF, web‑ready PNG.

10. Web Authoring – HTML & CSS

10.1 HTML – Structure & Common Tags

<!DOCTYPE html>
<html>
<head>
<title>My Page</title>
<meta charset="UTF-8">
<link rel="stylesheet" href="styles.css">
</head>
<body>
<h1>Welcome</h1>
<p>This is a paragraph.</p>
<img src="photo.jpg" alt="Sample image">
<a href="https://www.example.com">Visit example</a>
<ul>
<li>Item 1</li>
<li>Item 2</li>
</ul>
<table>
<tr><th>Name</th><th>Score</th></tr>
<tr><td>Alice</td><td>85</td></tr>
</table>
</body>
</html>

• Semantic tags – <header>, <nav>, <section>, <article>, <footer> improve accessibility and SEO.
• Attributes – src, href, alt, title.

10.2 CSS – Styling the Web Page

/* External stylesheet (styles.css) */
body {
font-family: Arial, sans-serif;
background-colour: #f9f9f9;
margin: 20px;
}
h1 {
colour: #003366;
text-align: centre;
}
p.intro {
font‑size: 1.1em;
line‑height: 1.5;
}
a {
colour: #0066cc;
text‑decoration: none;
}
a:hover {
text‑decoration: underline;
}

• Selectors – element, class (.intro), ID (#menu), descendant (nav ul li).
• Properties – colour, background‑colour, margin, padding, border, font‑size, display, float.
• Advantages of CSS: separates content from presentation, reduces file size, enables site‑wide style changes.
• Disadvantages: requires understanding of cascade and specificity; older browsers may need fall‑backs.

10.3 Publishing Considerations

• File formats – HTML, CSS, JPG/PNG, GIF, SVG, PDF for downloadable resources.
• Accessibility – alt text for images, sufficient colour contrast, logical heading order.
• Responsive design – media queries to adapt layout for mobile devices.
• Search Engine Optimisation (SEO) – use meta‑tags, meaningful URLs, keywords.

11. Emerging Technologies

• Artificial Intelligence (AI) – machine learning, natural language processing; embedded in predictive text, image recognition, chat‑bots.
• Extended Reality (XR) – Augmented Reality (AR) and Virtual Reality (VR) for training, simulation, entertainment.
• Cloud Computing – SaaS, PaaS, IaaS; advantages: scalability, reduced hardware costs; disadvantages: dependence on Internet, data‑privacy concerns.

12. Systems Development Life‑Cycle (SDLC) & Evaluation

1. Analysis – Identify problem, gather user requirements, define objectives.
2. Design – Create flowcharts, wireframes, data models; decide on hardware & software specifications.
3. Implementation (Development) – Write or configure the software; integrate with existing systems.
4. Testing – Unit, integration, system and user‑acceptance testing; fix defects.
5. Maintenance – Update, debug, add features, provide support.

12.1 Evaluation Criteria (AO3)

13. Practical Skills Expected for IGCSE

• Selecting the most appropriate application software for a given task.
• Using built‑in functions (formulas, macros, templates, styles) to automate work.
• Importing, exporting and converting data between different file formats (e.g., CSV ↔ XLSX, DOCX ↔ PDF).
• Creating and formatting documents, spreadsheets, presentations and databases to a professional standard.
• Applying basic security measures – password protection, file encryption, user permissions.
• Evaluating software solutions against criteria such as cost, compatibility, usability, reliability and security.
• Producing a simple web page using HTML and CSS, ensuring accessibility and responsive design.

14. Structured Example – Produce a Monthly Expense Report

1. Identify the task – Record, calculate and visualise personal expenses for one month.
2. Select the application – Spreadsheet software (e.g., Microsoft Excel, Google Sheets).
3. Data entry – Use the keyboard to type expense categories in column A and amounts in column B.
4. Processing – Apply formulas:

   • Total: =SUM(B2:B15)
   • Average: =AVERAGE(B2:B15)
   • Conditional formatting – highlight amounts > £200 in red.

5. Output – Insert a pie‑chart to visualise spending categories; print the report or share it via email.
6. Storage – Save the workbook on SSD (local) and back it up to a cloud drive.
7. Evaluation – Check that the spreadsheet meets the evaluation criteria (accuracy, readability, security, ease of update).

Key Points Demonstrated

• Application software translates user intent into computer actions.
• It utilises hardware resources (CPU, RAM, storage, I/O) managed by the OS.
• Built‑in features (formulas, charts, templates) increase productivity and accuracy.
• Evaluation ensures the solution is fit for purpose.

15. Summary

• Computer systems combine hardware, system software and application software to perform tasks.
• Application software sits atop the OS, using hardware to deliver specific services such as document creation, data analysis, communication and web publishing.
• Understanding hardware, I/O devices, storage media, networks, safety & security, and the full range of application software enables learners to select, use and evaluate the right tools for any real‑world problem.
• The SDLC provides a systematic framework for developing reliable, user‑focused applications, while evaluation criteria ensure that solutions are appropriate, secure and cost‑effective.