Year 8 · Autumn 1
Computer Systems · Lesson 5 of 5
Operating systems, applications and utilities
TheoryTopic 8 Inside the computerTopic 10 Software
Year 8 · Computer Systems · Lesson 5 of 5
You will learn to
- Explain the difference between system software and application software.
- Describe what the operating system does when you double-click a file.
- Identify a utility, like antivirus or backup, and the problem it solves.
- Compare a compiler and an interpreter, using the translators toy.
Year 8 · Computer Systems · Lesson 5 of 5
Success criteria
You have got it when you can say:
- I can sort software into system, application and utility.
- I can name three jobs of the operating system.
- I can explain that Python uses an interpreter, so it stops at the first error.
Year 8 · Computer Systems · Lesson 5 of 5
Retrieval starter
Questions from before. Write your answers, then show them.
- Last lesson
A AND B, with A = 1 and B = 0, gives…
A 1B 0
B. 0
- Earlier this unit
A microphone hearing your voice is…
A ProcessB InputC Output
B. Input
- Last year
Logging into a friend's account 'just to look' is…
A Against the Computer Misuse ActB Fine if you don't change anything
A. Against the Computer Misuse Act
Year 8 · Computer Systems · Lesson 5 of 5
Key words (1 of 5)
- embedded system
- A small computer built into a device for one job.
- operating system
- System software that manages hardware and runs programs.
- drivers
- Small program that lets the operating system talk to a device.
- CPU
- Central Processing Unit: the processor that runs instructions.
Year 8 · Computer Systems · Lesson 5 of 5
Key words (2 of 5)
- Register
- Tiny storage inside the CPU, like the PC or ACC.
- Bus
- A set of wires that carries addresses, data or control signals between parts of the computer.
- RAM
- Random Access Memory: fast, volatile working memory.
- Volatile
- Loses its contents when the power goes off.
Year 8 · Computer Systems · Lesson 5 of 5
Key words (3 of 5)
- Cache
- Small, very fast memory on the CPU chip.
- Clock speed
- How many cycles a CPU does per second, in GHz.
- Software
- Programs: instructions that tell hardware what to do.
- Driver
- Small program that lets the operating system talk to a device.
Year 8 · Computer Systems · Lesson 5 of 5
Key words (4 of 5)
- Open source
- Software whose code anyone can see, change and share.
- Machine code
- Binary instructions the CPU actually runs.
- Compiler
- Translates a whole program into machine code before it runs.
- Interpreter
- Translates and runs code one line at a time.
Year 8 · Computer Systems · Lesson 5 of 5
Key words (5 of 5)
- IDE
- Integrated Development Environment: the program you code in.
The explanation · step 1 of 2
Embedded systems
An embedded system is a small computer inside a device, doing one job: a microwave, a car's brakes, a micro:bit. Most computers in the world are embedded.
The explanation · step 2 of 2 · part 1 of 2
The operating system
The operating system (Windows, macOS, Android…) sits between the hardware and every app. Its jobs:
The explanation · step 2 of 2 · part 2 of 2
The operating system (continued)
- User interface: windows, icons, menus, or typed commands.
- Memory management: which program gets which part of RAM.
- Multitasking: switches between programs thousands of times a second.
- Peripherals: uses drivers to talk to printers, keyboards, graphics cards.
- Files: folders, names, copying, deleting.
- Users: accounts, passwords, who can see what.
Year 8 · Computer Systems · Lesson 5 of 5
Try it: Compiler vs interpreter
Year 8 · Computer Systems · Lesson 5 of 5
Quick quiz · 1 of 3
Round-robin scheduling means…
- A Each program gets a short time slice in turn
- B The biggest program always runs first
- C Programs run truly at the same time on one core
A. Each program gets a short time slice in turn
Everyone gets a turn, then goes to the back of the queue.
Year 8 · Computer Systems · Lesson 5 of 5
Quick quiz · 2 of 3
An incremental backup copies…
- A Every file
- B Only the operating system
- C Only the files changed since the last backup
C. Only the files changed since the last backup
That's why it's small and quick, but restoring needs the whole chain.
Year 8 · Computer Systems · Lesson 5 of 5
Quick quiz · 3 of 3
Which is a feature of open-source software?
- A Its code is kept secret
- B Anyone can see and change the source code
- C It always costs money
B. Anyone can see and change the source code
Open source is about the code being open, not about price.
Year 8 · Computer Systems · Lesson 5 of 5
Exit ticket
Answer on paper before you go. Then check.
Which translator turns assembly into machine code?
A AssemblerB CompilerC Interpreter
A. Assembler One assembly instruction becomes one machine-code instruction.
Python in school usually runs with…
A An interpreterB A compiler
A. An interpreter It runs line by line and stops at the first error.
Year 8 · Computer Systems · Lesson 5 of 5
Homework and the challenge
Homework
Study pages 8 and 9 to the quiz.
End-of-unit challenge
Label and explain a system diagram, then solve three logic-circuit puzzles.