Who keeps the apps apart?
You run a game, a browser and a chat at once. The chat app cannot read your browser's secrets. Why not?
Something in the middle keeps them apart. Today you meet it and its ten jobs.
Key words
| Word | What it means |
|---|---|
| Function | A job that something does. |
| Network | Devices joined together so they can share data. |
| Operating system | The main software that runs a device. Short form: OS. |
| Client side OS | An OS for a desktop PC or laptop, such as Windows, macOS or Linux. |
| Mobile OS | An OS for a phone or tablet, such as Android or iOS. |
| Server side OS | An OS for a server, such as Windows Server or Linux. |
| Server | A computer that serves data or services to other devices. |
| Memory | Where a device keeps what it is working on right now. |
| Driver | Software that lets the OS talk to a piece of hardware. |
| Signed driver | A driver with a mark that proves who made it. |
| Side-channel attack | An attack that learns secrets from how a processor behaves. |
| Graphical user interface | A screen with icons and windows. Short form: GUI. |
The cells students fill in are left blank in this preview.
By the end of this lesson
Note
I can name three types of operating system and describe ten functions of an OS, including how it protects security.
Starter: what you already know
Have a go
Starter: what you already know
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.
Three types of OS
Client side OS runs on desktop PCs and laptops. Examples are Windows, macOS and Linux.
Mobile OS runs on tablets and phones. Examples are Android and iOS.
Server side OS runs on a server. It is a network operating system. Examples are Windows Server and Linux.
Functions 1 to 4
Security: the OS sets limits and controls to protect data and software. Zero trust is an example.
System performance: the OS sits between software and hardware, so they work well together.
Error detection: the OS spots faults in software and hardware.
GUI: the OS gives users a screen with icons and windows.
Functions 5 to 7
Memory management: the OS shares out memory. It stops one app reading another app's memory.
Processor management: security controls inside the processor add protection, for example against a side-channel attack.
Device management: the OS can apply controls when it uses hardware. For example, it can require signed drivers.
Functions 8 to 10
File management: the OS stores and finds data.
Program execution: the OS decides how and when users can run code, and what rights each program gets.
Input and output: the OS handles what goes in, such as keystrokes, and what comes out, such as pictures on the screen.