Name the five main functions of an operating system.

An operating system provides a user interface and manages memory and multitasking. The OS also manages peripherals and drivers, user accounts and files.

What is the purpose of a user interface?

A user interface lets a person give the computer commands and see its responses. The interface hides the complexity of the hardware from the user.

What features does a graphical user interface usually provide?

A graphical user interface uses windows, icons, menus and a pointer, known together as WIMP. Users select items on screen instead of typing commands.

What is a command-line interface?

A command-line interface is a text-based interface in which the user types commands for the OS to carry out. Each command must be typed with exactly the right spelling and format.

Why might an experienced technician prefer a command-line interface to a GUI?

Typed commands can be quicker for someone who knows them, and they can be combined into scripts to automate tasks. A command-line interface also uses far less memory and processing power.

OCR GCSE Computer Science J277

Systems Architecture

Topic overview CPU components and the fetch-execute cycle Factors affecting CPU performance Embedded systems

Memory and Storage

Topic overview RAM, ROM, cache and virtual memory Secondary storage: magnetic, optical and solid state Data units and storage capacity calculations Binary, denary and hexadecimal conversions Binary addition, overflow and binary shifts Character sets, ASCII and Unicode Bitmap images, colour depth and resolution Sound sampling, sample rate and bit depth Lossy and lossless compression

Computer Networks, Connections and Protocols

Topic overview LANs, WANs and network performance Client-server and peer-to-peer networks Network hardware, DNS, hosting and the cloud Star and mesh topologies Wired and wireless connections, IP and MAC addresses Protocols, standards and layers

Network Security

Topic overview Malware, social engineering and brute-force attacks Denial of service, data interception and SQL injection Identifying and preventing vulnerabilities

Systems Software

Topic overview User interfaces, memory management and multitasking Peripheral, user and file management Utility software

Ethical, Legal, Cultural and Environmental Impacts of Digital Technology

Topic overview Ethical and cultural issues in digital technology Environmental impact of digital technology Privacy and digital technology Computer Science legislation and software licences

Algorithms

Topic overview Abstraction, decomposition and algorithmic thinking Flowcharts, pseudocode and structure diagrams Trace tables and correcting algorithms Linear and binary search Bubble, merge and insertion sort

Programming Fundamentals

Topic overview Variables, constants, operators and assignment Sequence, selection and iteration Data types and casting String manipulation and file handling Arrays, records and SQL Functions, procedures and random numbers

Producing Robust Programs

Topic overview Defensive design, input validation and authentication Writing maintainable code Testing, errors and test data

Boolean Logic

Topic overview Logic gates and truth tables Combining gates in logic diagrams

Programming Languages and Integrated Development Environments

Topic overview High-level and low-level languages and translators The integrated development environment (IDE)

Systems Software

User interfaces, memory management and multitasking

3 things to know
J277/01

Overview

The functions of an operating system, graphical, command-line and voice interfaces, how memory is allocated and released, and how the OS makes multitasking possible.

What you need to know

Answer each one before you reveal it.

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Key term

How does an operating system manage memory and multitasking?

Key term

What does an operating system do, and what is its user interface for?

Key term

What is an operating system?

Questions from this subtopic

Each one with the model answer underneath.

1
What is an operating system?
Model answer
An operating system is system software that manages a computer's hardware and resources. The OS also provides a platform for applications to run on and an interface for the user.
2
Name the five main functions of an operating system.
Model answer
An operating system provides a user interface and manages memory and multitasking. The OS also manages peripherals and drivers, user accounts and files.
3
What is the purpose of a user interface?
Model answer
A user interface lets a person give the computer commands and see its responses. The interface hides the complexity of the hardware from the user.
4
What features does a graphical user interface usually provide?
Model answer
A graphical user interface uses windows, icons, menus and a pointer, known together as WIMP. Users select items on screen instead of typing commands.
5
What is a command-line interface?
Model answer
A command-line interface is a text-based interface in which the user types commands for the OS to carry out. Each command must be typed with exactly the right spelling and format.
6
Why might an experienced technician prefer a command-line interface to a GUI?
Model answer
Typed commands can be quicker for someone who knows them, and they can be combined into scripts to automate tasks. A command-line interface also uses far less memory and processing power.

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Systems Architecture

Memory and Storage

Computer Networks, Connections and Protocols

Network Security

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