I.13 Types of Software

⬆️ Back to: P-I.I. Introduction to Computing

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Page Outline — click a heading to jump. Past-paper questions sit in the last section.

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Exam pattern (2016–2026): 2021 Q3(c) IDEs (5) · 2024 MCQ Q4 (system software).

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1. Definitions

• Software: instructions, programs and data that tell hardware what to do; intangible.
• Program: one set of instructions for one task.
• Software: the wider term — one or many programs plus data and documentation.

2. Three Categories by Function

• 🧠 Stack: hardware → system software → applications; programming tools build both upper layers.

2.1 System software

• Operating system:
  • Schedules CPU, manages memory, files and I/O through a kernel.
  • Types: single/multi-user, single/multitasking, real-time, mobile.
  • Examples: Windows, macOS, Linux, Android, iOS.
• Device drivers:
  • Translate OS commands for one specific device.
  • Missing driver → device works partly or not at all.
  • Examples: printer, GPU, network drivers.
• Utilities:
  • Maintain or optimise the system.
  • Examples: antivirus (Windows Defender), compression (WinRAR), backup, disk cleanup.

2.2 Programming software

• Compiler: translates the whole program first → standalone executable (GCC, javac).
• Interpreter: translates and runs line by line (CPython).
• Assembler: assembly mnemonics → machine code (NASM, MASM).
• Debugger: breakpoints, step-through, inspect variables (GDB).
• IDE: editor + compiler + debugger in one (Visual Studio, Eclipse, PyCharm).
• Why separate from system software:
  • Used by developers, not every user.
  • Its output is other software.
  • The computer runs fine without it.

2.3 Application software

• General-purpose: Word, Excel, browsers — cheap, broad, not specialised.
• Specialised: QuickBooks, AutoCAD, radiology software — deep features, costlier.
• Custom/bespoke: built for one organisation (airline booking, bank core system) — exact fit, high cost.

3. System vs Application Software

• Dependency is one-way: an app makes system calls for disk, memory and screen.
• That is why a Windows .exe will not run on Linux.

4. Compiler vs Interpreter

• 🧠 Compilers run faster, debug slower; interpreters debug faster, run slower.
• Hybrid: Java → bytecode → JVM interprets or JIT-compiles.

5. Copyright and Licensing

5.1 Copyright vs licence

• Copyright: automatic legal right from the moment code is written.
  • Gives the owner control of copying, distributing, modifying.
  • Berne Convention (Pakistan is a party); Pakistan: Copyright Ordinance 1962, IPO-Pakistan.
• Licence: the permission the owner grants to others.
  • Does not transfer ownership.
• 🧠 Copyright = ownership; licence = what others may do.

5.2 Licensing models

• Two separate questions: is the source open? must you pay?
• Red Hat Enterprise Linux: paid, yet open-source.

5.3 Public domain vs open-source

• Public domain: no copyright (expired or waived, e.g. CC0); no conditions; anyone can close it and sell it.
• Open-source: still copyrighted; licence grants rights with conditions (attribution, maybe share-alike).

5.4 Copyleft vs permissive

• Triggered by distribution, not internal use (AGPL closes this for web services).
• Weak copyleft: LGPL, Mozilla Public License.

5.5 Other axis — platform

• Native: installed on one OS (Word desktop).
• Web/cloud: runs in a browser (Google Docs, Gmail).
• Mobile: phone/tablet apps.

6. Classifying One Product on Every Axis

• Linux: system software (OS kernel) + open-source (GPLv2) + native.
  • Runs on x86, ARM, RISC-V, mainframes; Android's kernel; almost all TOP500 supercomputers.
• MS Word: application + proprietary + native (web version in Microsoft 365).
• Python: see I.14.

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7. ⚠️ MCQ Traps

• Compilers, IDEs are programming software, not system software.
• Device driver = system software.
• Compiler = fast run, slow debug.
• Open-source is about source, not price.
• Freeware ≠ open-source.
• Copyright ≠ licence; open-source is still copyrighted.
• Public domain ≠ open-source.
• GPL forces openness; MIT does not.

8. ✅ Self-Test Questions (with Answers)

Q1. Three categories of software with one example each.

• System: Windows. Programming: GCC. Application: MS Word.

Q2. Where do compilers and IDEs fit, and why separately?

• Programming software.
• Different user (developer), different output (other software), not needed to run the PC.

Q3. System vs application software using dependency.

• Apps need the OS; the OS does not need apps.
• Use the table in section 3.

Q4. Compiler vs interpreter on speed and debugging.

• Use the table in section 4.

Q5. When is a specialised application better than a general one?

• Case: a Lahore architecture firm uses AutoCAD/Revit, not MS Paint.
  • Real-world units and exact dimensions.
  • Domain intelligence (a wall knows it is a wall; changes update every view).
  • Industry file formats (DWG/IFC) for engineers and approvals.
  • Errors in a general tool risk safety and legal problems.
• Rule: general for common, low-budget tasks; specialised when accuracy, compliance or interoperability matter.

Q6. Proprietary, open-source, freeware, shareware — one example each.

• Use the table in 5.2.

Q7. Classify Linux on three axes.

• System (OS) + open-source GPLv2 + native.

Q8. Copyright vs licence.

• Ownership vs permission; see 5.1.

Q9. Public domain vs open-source.

• No copyright vs copyrighted with licence; see 5.3.

Q10. Copyleft vs permissive licence.

• GPL (Linux) vs MIT (React); see 5.4.

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9. 📜 Past-Paper Questions & MCQs (CSS 2016–2026)

2021 · Paper-I · Q3(c) · 5 marks

Q. What are IDEs? How do they help in software development? List the IDEs you have used.

Quick revision and exam-ready model

Quick revision — key points

• Define IDE as integrated developer toolkit
• Editing, syntax checking and completion
• Build, debugging, testing and version control
• Name only IDEs actually used

Exam-ready answer — structured

Introduction / direct answer: An Integrated Development Environment (IDE) combines tools for writing, building, testing and debugging software in one interface.

Main explanation

• Typical facilities include syntax highlighting and completion, project management, compiler/interpreter or build-system integration, breakpoints and variable inspection, refactoring and version-control integration. It reduces repetitive setup and helps diagnose defects early.
• Examples: Visual Studio, IntelliJ IDEA, Eclipse, PyCharm and Android Studio. A candidate may name the IDEs they have genuinely used; do not claim personal experience falsely.

MCQs

2024 P-I · Q4. What is an example of system software from the list below?

• (A) Windows ✅
• (B) Google Chrome
• (C) Adobe Photoshop
• (D) None of these
• Answer: (A) Windows.
• Why: an operating system is the main example of system software. Chrome and Photoshop are application software.