Types and Components of Computer Systems
This chapter covers the building blocks of computer systems. It explains the difference between hardware and software, the main components of a computer system, operating systems and user interfaces, common types of computer, and important emerging technologies such as AI, AR and VR.
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1.1 Hardware and software
This part of the chapter introduces the difference between the physical parts of a computer system and the programs that tell the computer what to do.
Hardware
Hardware means the physical parts of a computer system — the parts you can actually see or touch.
Examples of external hardware
- keyboard
- mouse
- camera
- monitor
- printer
- plotter
Examples of internal hardware
- motherboard – the main circuit board; connects all parts together
- CPU / processor – processes instructions and controls operations
- RAM – temporary memory used while programs are running
- ROM – permanent memory storing important start-up instructions
- graphics card – sends graphics to a screen
- sound card – handles sound input and output
- NIC (network interface card) – allows connection to a network
- HDD / SSD – used to store data and software permanently
Software
Software means the programs that control the computer and process data.
There are two main types of software:
1. Applications software
Application software helps the user carry out specific tasks.
Word processing
Create, edit and format text documents such as letters, reports and essays.
Spreadsheet
Organise and manipulate numerical data using formulae, calculations, graphs and what-if models.
Database software
Store, organise and search data in tables; records can be added, edited, deleted, queried and used in reports.
Graphics editing
Create or modify bitmap and vector images, for example by changing colours, shapes or other image features.
Video editing
Edit video clips by adding, removing or rearranging sections and adding titles, transitions, effects or sound.
Audio editing
Edit and manipulate sound, for example by trimming tracks, changing volume, combining audio or converting file formats.
CAD
Computer-aided design is used to create, modify and analyse 2D or 3D designs and drawings.
Control and measurement software
Works with sensors to measure physical quantities and can control processes by comparing sensor readings with stored values.
Apps and applets
Apps perform useful tasks such as banking or streaming; applets are smaller programs designed for a specific task, often used within a web page.
2. System software
System software manages the computer and provides a platform for other software to run.
- Operating system (OS) – manages the computer’s basic functions, including input/output, running programs, error handling and security.
- Utility software – helps maintain and manage the computer, for example antivirus, backup, file management and disk maintenance tools.
- Device driver – allows a hardware device, such as a printer, to communicate with the operating system.
- Compiler – translates a program written in a high-level language into machine/object code that the computer can execute.
- Linker – combines one or more compiled object files or program modules into a single program that can be run.
Analogue and digital data
Digital data
Computers understand digital data, which is based on binary (0 and 1). Digital data has discrete values.
Analogue data
Analogue data changes continuously and smoothly.
1.2 Main components of computer systems
A typical computer system is made up of several key components that work together to accept input, process data, store information and produce output.
CPU
The CPU (central processing unit) is the “brain” of the computer.
Its job is to:
- interpret instructions
- execute instructions
- control other parts of the system
Main parts of the CPU:
Control Unit (CU)
Controls operations and input/output.
Arithmetic and Logic Unit (ALU)
Performs calculations and logical decisions.
Registers
Small storage locations inside the CPU.
Internal memory
RAM
- temporary memory
- stores data and programs currently being used
- can be read from and written to
- volatile memory, so contents are lost when power is off
ROM
- permanent memory
- stores important start-up instructions
- non-volatile memory, so contents remain when power is off
- usually stores the BIOS
BIOS and CMOS
BIOS (Basic Input/Output System) tells the computer what to do when it starts up. It checks hardware and then loads the operating system into RAM.
CMOS stores things like:
- date
- time
- system settings
Input and output devices
Input devices
Used to enter data into the computer.
Output devices
Used to show the results of processing.
Backing storage
Backing storage is used to store large amounts of data permanently.
Key points:
- backing storage is non-volatile
- it has much larger capacity than RAM and ROM
- it is slower than RAM
- it is cheaper per byte
- data usually needs to be moved into RAM before the CPU can use it directly
Fixed storage
Fixed storage is usually inside the computer.
Removable storage
Removable storage can be taken out and used as a backup.
1.3 Operating systems
An operating system allows the computer to work properly and lets the user communicate with the machine.
What is an operating system?
An operating system (OS) is system software that allows the computer to work and allows the user to communicate with the computer.
Main functions of an operating system
- controls input, output and storage devices
- manages the loading and running of programs
- handles errors
- maintains security
- keeps a computer log
- provides a user interface
User interfaces
The book covers four types of user interface.
1. Command Line Interface (CLI)
The user types commands.
Features
- commands must be typed
- user communicates directly with the computer
- often used by technicians and programmers
Advantages
- direct control
- not limited to icons/menus
- useful for advanced users
Disadvantages
- commands must be memorised
- easy to make typing mistakes
- slower for many users
2. Graphical User Interface (GUI)
The user interacts using icons, windows, menus and a pointing device. This is often called WIMP: Windows, Icons, Menus, Pointing device.
Advantages
- easy to use
- no need to memorise commands
- more user-friendly
Disadvantages
- uses more memory
- can be slower than CLI
- user is limited to the options shown
3. Dialogue-based interface
The user gives commands using voice.
Examples
Advantages
- hands-free use
- useful for disabled users
- can be convenient
Disadvantages
- may not recognise commands properly
- background noise can cause problems
- user must know what commands to say
4. Gesture-based interface
The user controls the system using movements of hands, fingers, head or feet.
Examples
- hand gesture to change car settings
- foot movement to open a car boot
Advantages
- natural way to interact
- no physical contact needed
- no need for a keyboard or mouse
Disadvantages
- may detect accidental movement
- usually only works close to the sensor
- only certain gestures may be recognised
1.4 Types of computer
The chapter divides computers into desktop computers and mobile computers.
Desktop computers
A desktop computer usually has separate:
Advantages of desktops
- easier to upgrade
- usually cheaper to repair
- often better value for the same price
- stable internet connection is common
Disadvantages of desktops
- not portable
- lots of wires
- take up more space
Uses of desktops
- office work
- school/education
- gaming
- general entertainment
Mobile computers
The book includes four types:
Laptop
A laptop has the screen, keyboard, pointing device and processor in one unit.
Advantages
- portable
- less space needed
- useful with Wi-Fi
- easy to carry around
Disadvantages
- easier to steal
- limited battery life
- harder to upgrade
- keyboard/trackpad can be less comfortable
Uses
- office work
- education
- gaming
- entertainment
- control and monitoring
Smartphone
A smartphone is a mobile phone with an operating system and apps.
Typical features
- touch screen
- cameras
- internet access
- Bluetooth
- sensors such as accelerometer and proximity sensor
- flash memory and cloud syncing
Advantages
- very portable
- internet access on the move
- can make calls and run apps
- useful sensor-based features
Disadvantages
- small screen
- slower typing
- battery drains quickly during heavy use
- easier to lose or steal
Tablet
A tablet is like a larger touch-screen mobile computer.
Typical features
- touch screen
- virtual keyboard
- Wi-Fi or mobile network access
- cameras and sensors
Advantages
- very quick to start
- lightweight
- easy to use
- long battery life
Disadvantages
- typing can be slow
- storage may be limited
- some software works better on laptops
- mobile internet can be expensive
Phablet
A phablet is a hybrid of a smartphone and a tablet.
- bigger than a smartphone
- smaller than a tablet
Main uses of smartphones, tablets and phablets
- entertainment
- gaming
- internet browsing
- emails
- GPS/maps
- social networking
- online banking
- VoIP/video calls
- education
- remotely controlling devices
1.5 Emerging technologies
This section covers artificial intelligence and extended reality, including augmented reality and virtual reality.
Artificial intelligence (AI)
AI is when a machine or application carries out tasks that require some level of intelligence.
Examples from the chapter:
Positive effects
- can improve safety
- can improve quality of products and services
- useful in dangerous environments
- can help people with disabilities
Examples
- driverless vehicles
- robotic help for amputees
- robots doing dangerous jobs like bomb disposal
Negative effects
- may cause job losses
- people may become too dependent on technology
- human skills may be lost over time
Extended reality (XR)
XR is a general term for immersive technologies.
This chapter focuses on AR and VR.
Augmented reality (AR)
AR adds digital information to the real world.
Features of AR
- combines real and virtual elements
- overlays text, images or animation onto real scenes
- can be viewed through special glasses or a smartphone screen
- user is still aware of the real world
Uses of AR
- safety and rescue
- entertainment
- shopping and retail
- healthcare
Virtual reality (VR)
VR places the user inside a fully virtual environment.
Features of VR
- user is fully immersed in a digital world
- usually needs a headset
- gives a 360° experience
Uses of VR
- military training
- education
- healthcare
- entertainment and gaming
- heritage/tourism
- business training
- engineering
- sport
- media
- scientific visualisation
Quick revision points
Students should be especially able to:
- define hardware and software
- distinguish between application software and system software
- explain the difference between analogue and digital data
- compare RAM and ROM
- explain the role of the CPU
- compare input devices and output devices
- explain what backing storage is
- describe the functions of an operating system
- compare CLI and GUI
- compare desktop, laptop, smartphone, tablet and phablet
- explain AI, AR and VR