What an operating system does

The computer's traffic controller

An operating system (OS) is system software. It manages the hardware, runs application software and gives you a user interface. Windows, macOS, Linux, Android and iOS are all operating systems.

Your book calls the OS the central system controller. Like a traffic controller, it decides which task runs first, how memory is used, and which devices, such as a printer or speakers, are active. So the computer stays smooth even with many tasks running.

Hardware cannot understand human language. The OS acts as a translator. When you click an icon or type, it turns your action into instructions the hardware understands. Press A and the OS sends the binary code (01000001)₂, which the screen shows as A.

In schools and offices many people share one computer. The OS creates and manages separate user accounts, keeps each user's files private, shares resources fairly, and protects shared resources from unauthorized access.

Each account has its own desktop, files, settings and password. In Windows you open Settings or Control Panel, choose User Accounts, then Add New User. You enter a username, a password and an account type: Standard, Administrative or Guest.

Three jobs: controller (decides what runs and when), translator (your clicks into hardware instructions), guard (separate, private accounts on a shared computer).

Key terms

Operating system

Managing hardware, running applications and giving a user interface.

Central system controller

Deciding task order, memory use and which devices are active.

User account

Giving each user a separate desktop, files, settings and password.

Unauthorized access

Use of shared resources by someone without permission.

Short questions with model answers

1. Q1. Short Question 1 (p. 17): why is the OS called the central controller?

   • Name what it decides.
   • Give the result.

   Like a traffic controller, it decides task order, memory use and active devices, so everything runs smoothly together.

2. Q2. Short Question 3 (p. 17): give one way to create a new user account in Windows.

   • Open the right place.
   • Add the user.

   Settings or Control Panel → User Accounts → Add New User → username, password, type (Standard, Administrative or Guest).

Common mistakes

• ✗ Counting an application such as Photoshop as an operating system.

  ✓ Photoshop runs on an OS. The OS examples in your book are Windows, macOS, Linux, Android and iOS.

• ✗ Writing that on a multi-user computer all users share the same files.

  ✓ The OS keeps each user's files private. It shares resources fairly, not personal files.

• ✗ Saying user accounts are created in Task Manager or BIOS settings.

  ✓ Your book names Settings or Control Panel, then User Accounts.

MCQs

1. 1. Which is NOT an example of an operating system?

   1. (a) Linux
   2. (b) Windows
   3. (c) Photoshop
   4. (d) macOS
   Show answer

   (c) Exercise MCQ 1 (p. 16); key p. 18. Photoshop is an application.

2. 2. In multi-user environments, the OS ensures:

   1. (a) Equal access and data privacy
   2. (b) All users share the same files
   3. (c) Hardware is never used
   4. (d) Internet speed is increased
   Show answer

   (a) Exercise MCQ 2 (p. 16); key p. 18; 1.1.3, p. 3.

3. 3. In Windows, user accounts can be created via:

   1. (a) Task Manager
   2. (b) Control Panel or Settings
   3. (c) Disk Management
   4. (d) BIOS settings
   Show answer

   (b) Exercise MCQ 3 (p. 16); key p. 18; 1.1.4, p. 3.

4. 4. When you press A, what does the OS send so the screen can show it?

   1. (a) The word A in English
   2. (b) A picture of the key
   3. (c) A password
   4. (d) The binary code (01000001)₂
   Show answer

   (d) Do You Know, p. 2: hardware understands only 0 and 1.

5. 5. Which account type is NOT listed in your book for a new Windows user?

   1. (a) Standard
   2. (b) Administrative
   3. (c) Guest
   4. (d) Teacher
   Show answer

   (d) 1.1.4, p. 3 lists Standard, Administrative and Guest.

Quick revision

• The OS is system software that manages hardware, runs applications and gives a user interface.
• As central controller it decides task order, memory use and active devices; as translator it turns your actions into hardware instructions.
• On a shared computer it gives separate, private accounts, shares resources fairly and blocks unauthorized access.