Computer Software – Complete Notes for IBPS, SSC, RRB & Govt Exams

Introduction: Why Computer Software is a High-Scoring Chapter

Every function a computer performs — from turning on to browsing the internet, from processing a bank transaction to running a railway booking system — is driven by software. Without software, hardware is an expensive collection of metal and silicon with absolutely no capability.

In government job exams, Computer Software is tested because it is directly relevant to banking, railway, and government office environments. Questions appear in formats like:

• "Which of the following is NOT System Software?" → MS Word (it is Application Software)
• "Which software directly controls hardware?" → Operating System / Device Drivers
• "VLC Media Player is an example of ___" → Freeware / Application Software
• "Linux is an example of ___" → Open Source Software
• "What is the purpose of a Disk Defragmenter?" → Rearranges fragmented files for efficiency

This chapter connects directly to the Operating System chapter (Chapter 10) and is one of the broadest topics — touching hardware control, user applications, and system maintenance. Master this chapter and you will score consistently from this section in every exam.

What is Software? Definition and Importance

Software is defined as a collection of programs, data, and related documentation that tells a computer what to do and how to do it. Unlike hardware (which you can physically touch), software is intangible — it exists as code stored on storage media or in memory.

Formal Definition:

Software is the set of instructions, programs, and associated data that directs the hardware to perform specific tasks and enables users to interact with the computer system.

Why is software important?

• Without software, a computer is a useless pile of hardware — it cannot even start
• Software defines the capabilities of a computer system
• The same hardware can do completely different things depending on the software installed
• Software is what the user actually interacts with — the operating system, apps, games, and websites

The Software-Hardware Relationship:

User ↔ Software (Application) ↔ System Software (OS) ↔ Hardware (CPU, RAM, HDD)

Software acts as the interface layer between the user and the hardware.

Hardware vs. Software - Key Difference

Types of Software - Complete Classification

Software is broadly classified into three main categories:

SOFTWARE

├── A) System Software

│     ├── Operating System

│     ├── BIOS

│     ├── Device Drivers

│     ├── Language Translators

│     ├── Linker

│     └── Loader

├── B) Application Software

│     ├── General Purpose (Word, Excel, Browser)

│     └── Specific Purpose (Payroll, Hotel Management)

└── C) Utility Software

      ├── Antivirus

      ├── Disk Defragmenter

      ├── Disk Compression

      └── Backup Tools

A) System Software

System Software is the category of software that directly controls, manages, and operates the computer hardware. It works in the background, enabling application software and the user to interact with the hardware.

Key characteristics:

• Works closest to the hardware
• Generally not used directly by end users
• Must be present for the computer to function
• Manages resources (CPU, memory, I/O devices)

Operating System (OS)

The Operating System is the most critical piece of system software. It is the master control program that manages all hardware resources and provides a platform for application software to run.

(Full detail in Chapter 10 — Operating Systems)

BIOS (Basic Input/Output System)

BIOS Boot Process: Power ON → BIOS/UEFI runs → POST checks hardware → BIOS loads OS bootloader → OS loads into RAM → User sees desktop

Device Drivers

Without a device driver: The OS cannot communicate with the device — it either doesn't work at all or works with very basic functionality.

Language Translators

(Full detail in Chapter 8 — Computer Languages)

Linker

The Linker is a system program that combines multiple object code modules (output of a compiler) into a single, complete executable program. Large programs are written in multiple files — the linker joins them together.

Process: Source Code → Compiler → Object Code → Linker → Executable File (.exe)

Loader

The Loader is the component of the OS responsible for loading executable programs into main memory (RAM) so the CPU can begin executing them.

Process: Executable File → Loader → RAM → CPU executes

When you double-click an application icon, the Loader is what copies the program from the hard disk into RAM and hands control to the CPU.

B) Application Software

Application Software is software that helps users perform specific real-world tasks. Unlike system software (which works with hardware), application software works directly with users to accomplish goals — writing documents, managing finances, playing games, browsing the internet.

Key characteristics:

• Directly used by end users
• Performs specific user-defined tasks
• Cannot function without system software (OS) being present
• Can be general-purpose or specific-purpose

General Purpose Application Software

General Purpose Application Software is designed to perform a wide range of tasks and can be used across many different types of work.

Specific Purpose Application Software

Specific Purpose Application Software is designed to solve one specific problem or serve one particular industry — it cannot be used for general tasks.

C) Utility Software (System Utilities)

Utility Software (also called System Utilities) is a category of software designed to support, optimise, and maintain the computer system — neither fully system software (doesn't control hardware directly) nor application software (doesn't help users with specific tasks like writing documents). Utilities work in the background to keep the system running efficiently.

Important Utility Programs and Their Purpose

What is Disk Fragmentation? Over time, as files are created, modified, and deleted, pieces of files get scattered across different areas of the hard disk. This is called fragmentation. A fragmented disk takes longer to read files because the read/write head must jump to different locations. Disk Defragmentation rearranges these scattered pieces so related data is stored contiguously, improving read speed.

Note: SSDs do NOT need defragmentation — they have no moving read/write heads, and defragmenting actually wears out the flash memory cells faster. Windows automatically skips defragmentation for SSDs.

Other Software Categories

Firmware

Freeware

Shareware

Open Source Software

Proprietary Software

CAD (Computer-Aided Design)

Software Licensing Terms

Memory Tricks

🔑 Three Types of Software — "SAU":

System Software | Application Software | Utility Software Mnemonic: "Students Always Use" software every day

🔑 System Software Sub-types — "OBDTLL":

OS | BIOS | Device Drivers | Translators | Linker | Loader Mnemonic: "Oh Big Dogs Take Long Leaps"

🔑 Freeware vs Shareware vs Open Source:

Freeware = FREE always (but closed source) Shareware = FREE to SHARE temporarily (try then buy) Open Source = OPEN to see and change the code

🔑 General Purpose Application Software — "WSPDGMW":

Word Processor | Spreadsheet | Presentation | DBMS | Graphics | Multimedia | Web Browser

🔑 Key Utility Software — "DAB DCT":

Disk Compression | Antivirus | Backup | Defragmenter | Cleaner | Text Editor

🔑 BIOS Acronym:

Basic Input Output System — "The BIOS starts it all" First software to run on startup → performs POST → loads OS

One-Liner Recap (Quick Revision)

1. Software is the intangible collection of programs, instructions, and data that tells computer hardware what to do, acting as the interface between the user and the hardware.
2. System Software directly controls and manages computer hardware — it includes the Operating System, BIOS, Device Drivers, Language Translators, Linker, and Loader.
3. The Operating System (OS) is the most critical system software — it manages all hardware resources and provides a platform for all application software to run.
4. BIOS (Basic Input/Output System) is the first software to run when a computer powers on — it performs the POST (Power-On Self Test) and then loads the Operating System.
5. Device Drivers are system software that act as translators between the Operating System and specific hardware devices like printers, graphics cards, and webcams.
6. A Linker combines multiple compiled object code files into one single executable program, while a Loader copies the executable from disk into RAM for the CPU to execute.
7. Application Software helps users perform specific real-world tasks and can be either General Purpose (Word, Excel, browser) or Specific Purpose (payroll, hotel management, Tally).
8. General Purpose Application Software includes Word Processors (MS Word), Spreadsheets (MS Excel), Presentations (MS PowerPoint), DBMS (MS Access), and Multimedia players (VLC).
9. Utility Software maintains and optimises the computer system — key utilities include Antivirus (removes malware), Disk Defragmenter (fixes fragmentation), Disk Cleanup (removes junk files), and Backup tools.
10. Firmware is software permanently embedded in hardware (stored in ROM/Flash ROM) — examples include BIOS chips, printer firmware, and router firmware.
11. Freeware is copyrighted software distributed completely free of charge, but the source code is NOT available — examples include VLC Media Player and Notepad++.
12. Shareware is available free of charge for a limited trial period, after which payment is required — the "try before you buy" model (e.g., WinRAR).
13. Open Source Software makes its source code publicly available for anyone to view, modify, and redistribute — key examples are Linux, Firefox, LibreOffice, and Python.
14. Proprietary Software is owned by a company with closed source code and requires a paid license to use — examples include Microsoft Windows and Adobe Photoshop.
15. Software Piracy refers to the illegal copying, distribution, or use of copyrighted software without authorisation — it is a punishable offence under the IT Act 2000 in India.

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