IGCSE ICT- chapter 1

Hardware

The physical components of a computer system which can be internal or external

Central Processing Unit (CPU)

INTERNAL COMPONENT. It is the computers "brain". It is an electric circuit board in a computer that can execute instructions from a computer program

Arithmetic Logic Unit (ALU)

It is a component of the CPU. Performs all arithmetic operations (for example, addition and subtraction) and all logic operations (such as sorting and comparing numbers)

Control Unit (CU)

It is a component of the CPU. Takes instructions and then decodes and executes it

mother board

INTERNAL COMPONENT. It is a printed circuit board found in all computers. It allows the processor and other hardware to function and communicate with each other.

processor

INTERNAL COMPONENT. a chip inside the CPU yhatcarries out insttructions from a program

Random Access Memory (RAM)

INTERNAL MEMORY.

Computer location where instructions and data are stored on a temporary basis when running applications

This memory is volatile which means that data is lost when the computer is turned off.

It can be written to or read from

Stores data, files, and part of the operating system that is currently in use

can be increased un size to improve operational speed of a computer

read-only memory (ROM)

INTERNAL MEMORY

Used to store information that needs to be permanent

The memory is non-volatile which means data is not lost when computer is turned off

These chips cannot be altered and only read from

Stores configuration data for a computer system, computer's BIOS (basic input/output system)

graphics card

HARDWARE COMPONENT.

processes images and videos for display on a monitor.

connects to motherboard

sound card

HARDWARE COMPONENT.

an integrated circuit board that provides a computer with the ability to produce sounds which can be heard through speakers or headphones.

they also allow users to give sound input via microphone and manipulate sound stored on a disk

Network Interface Card (NIC)

HARDWARE COMPONENT

links the computer or any other device to the network (wired or wireless)

Internal/Externam storage devices

HARDWARE COMPONENT

stores data permanently, HDD or USB

Input devices

HARDWARE COMPONENT

allows users to enter the data, keyboards/mouse

output devices

HARDWARE COMPONENT

displays or produces results, monitor/printer

camera

HARDWARE COMPONENT

captures images or video for input into the computer

software

programs for controlling the operation of a computer or processing of electronic data

application software

provides the services that the user requires to solve a task

ex- database management systems, word processing, speadsheet etc

system software

provides the services that the computer requires to operate

ex- compilers, linkers, device drivers etc

word processing

Application software that is used to create text documents such as letters, memos, and reports

spreadsheet

Application software for performing numerical calculations and analysis in a grid format

database management systems

Application software that handles the storing, retrieving, and managing of data in databases.

control/measurement

Application software that uses sensors to measure and control a system

Applets

Application software. They are small applications that perform a single task on a device

Apps

Application software which can perform a fairly substantial task

Video Editing Software

Application software for creating and manipulating videos.

graphics editing software

Application software for creating and modifying images

audio editing software

Application software for creating or modifying audio files

computer-aided design (CAD)

Application software which allows users to design and model objects in 2D or 3D

Compilers

System software that high level programming languages (HHL) into machine level code. Before compilation the program is called the source code and after compilation the code known as the object code

Linkers

System software that takes one or more object codes produced by a compiler and combines them into a single program

Device drivers

System software that enables one or more hardware devices to communicate with the computer's operating system. All hardware devices have their associated device drivers.

Utilities

System software that carries out specific tasks to manage, maintain and control computer resources.

ex- antivirus, anti-spyware, security, file management

Operating System (OS)

system software that runs in the background of a computer system while managing the basic functions to make the computers user-friendly.

Analogue data

Data that is continuous and varies smoothly over time

Digital data

Data that is discrete and represented in binary form (0 and 1)

Differences between analogue and digital data

1) Analogue data can have any value within a range while digital data has a limited set of values

2) digital data is less prone to noise and distortion compared to analogue data

3) Digital data can be easily manipulated, stores, and transmitted by computers unlike analogue data

Converting analogue to digital data

when data is being entered into a computer, in order for it to be processed, the analogue data needs to be converted into digital data using an analogue-to-digital converter

Converting digital to analogue data

when the computer is controlling a device (ex-motor) in order for the information to be processed, the digital data needs to be converted into analogue data using a digital-to-analogue converter

boot file

component that enables the system to initialise and start up

Basic Input/Output System (BIOS)

built-in program which initializes computer hardware and launches the operating system when the computer starts (USES ROM)

input device characteristics

1) any hardware component that allows you to enter data and instructions into a computer directly

2) can send data to another device but cannot receive it from another device

3) input devices can be fairly complex as they have to ensure the user can interact with the computer correctly

4) input devices are necessary for a computer to receive commands from its users

output device characteristics

1) any hardware device that takes output data from a computer and puts it into a human-readable format or uses the data to control another device

2) can receive data from another device but cannot send data to another device

3) less complex than input devices because they only have to turn computer signals into an output

4) output devices are needed by a computer to share the results of its processing with the humans, they are under control of the computer

Internal memory characteristics

1) RAM contents are lost when computer is powered down; ROM contents are readable only

2) RAM and ROM are much smaller memories than backing storage

3) data access time on RAM and ROM extremely fast

4) much more expensive per byte than backing storage devices

5) RAM and ROM are fixed inside the computer (internal memory)

6) RAM and ROM can be read directly by the CPU

backing storage characteristics

1) backing storage devices hold their contents permanently, even when powered down

2) have a larger capacity to store data than RAM or ROM

3) much slower data access time than RAM or ROM

4) much cheaper per byte than RAM or ROM

5) backing storage can either be fixed or removable (internal or external memory)

6) backing storage is not directly addressable by the CPU

general tasks for operating systems

1) control operation of input, output, and backing storage devices

2) dealing with errors that occur in application programs

3) maintaining the security of the whole computer system

4) maintaining a computer log

Command Line Interface (CLI)

interface that requires a user to type in instructions to choose options from menus, open software etc.

Graphical User Interface (GUI)

interface that allows a user to interact with the computer using graphics, and visual images, symbols, such as icons rather than having to type the commands

command line interface advantages

1) user is in direct communication with computer

2) user is not restricted to number of pre-determined options

3) possible to alter computer configuration settings

command line interface disadvantages

1) user needs to learn a number of commands to carry out basic operations

2) all commands need to be typed in which can take lots of time and can be error-prone

3) each command must be typed in using the correct format, spelling etc

graphical user interface advantages

1) user does not need to learn any commands

2) more user-friendly as icons are used to represent applications

3) simple pointing device used to click on the icon- easier than typing

graphical user interface disadvantages

1) uses up more computer memory than CLI

2) The user is limited to icons provided on the screen

3) needs complex operating system (windows) which can be slower to execute commands

who uses CLI?

Programmers, analysts and technicians.

Who uses GUI?

People who don't have, or don't need, great information about how computers work. For example: photo editors or gamers.

dialogue-based user interfaces

uses the human voice to give commands to the computer system (ex- amazon alexa, google now)

gesture-based interfaces

replies on human interaction by the moving of hands head or even feet. Uses the technique known as computer vision and image processing (ex- rotating finger clockwise near the radio to increase the volume)

dialogue-based user interface advantages

1) no need for driver to take their hands off the steering wheel

2) useful for people with disablities as many tasks can be carries out by the spoken word only

3) possible to use as security feature as voice recognition could be used to identify a person

dialogue-based user interface disadvantages

1) unreliable as commands may not be recognised, need to be repeated many times especially if theres background noise

2) can be quite complex to set up

3) user needs to know which commands can be used

gesture-based interface advantages

1) replaces mechanical input devices

2) no physical contact is required

3) natural interface for a human operator

4) no training needed to interface with the computer

gesture-based interface disadvantages

1) possible for unintentional movement to be picked up

2) only works fairly near the camera or sensor

3) may only accept a limited number, may take several attempts to figure out exactly what finger movements are recognised

desktop computer

a general-purpose computer that is made up of separate monitor, keyboard, mouse and processor unit

advantages of desktop computer vs laptop computer

1) easier and less expensive to upgrade and expand

2) they are usually fixed in one location, so there is less likelihood of them being damaged or stolen

3) spare parts and connections tend to be standardized, which usually results in lower costs

disadvantages of desktop computer vs laptop computer

1) not portable because they are made out of separate components

2) more complicated because all components need to be hooked up to wiring

3) clutters up the desk space

Main uses of desktop computers

1) office and business work (word processing, spreadsheets)

2) educational use

3) gaming device

4) general entertainment (streaming of tv programmes)

laptop computer

A portable computer where the monitor, keyboard, pointing device, and processor are all together in one single unit

key features you find in a laptop

1) lightweight

2) low power consumption- long battery life

3) low heat output

advantages of laptop computers vs desktop computers

1) portable

2) no trailing wires as everything is in one single unit

3) takes up less room on a desk

4) they can link to any multimedia system

disadvantages of laptop computers vs desktop computers

1) easier to steal

2) limited battery life so may need to carry a heavy power adaptor

3) keyboard and pointing device may sometimes be more awkward to use

4) not always possible to upgrade them (adding more RAM)

main uses of laptop computers

1) office and business work (spreadsheet, word processing)

2) educational use

3) gaming device

4) general entertainment (streaming TV programmes)

smartphones

allow normal phone calls to be made but also have an operating system so they can run many computer applications

features of smartphones

1) high-definition anti-glare displays

2) front- and back facing cameras

3) use flash memory and cloud storage

4) use sensors- proximity sensor (block unintended touches), accelerometer (movement and orientation in car games or when watching videos), sophisticated speech recognitions systems (siri)

advantages of smartphones

1) small in size, lightweight therefore easy to carry

2) make phone calls

3) connect to internet while on the move so they can be used almost anywhere

4) reasonable battery life compared to laptops

disadvantages of smartphones

1) small screens make it difficult to read pages

2) more difficult and slower to type things in compared to laptop or desktop

3) web browsing and photography can drain battery quickly

4) small so easier to lose or be stolen

5) memory size in most smartphones are not very large

tablet

a small, portable computer with a touch-sensitive screen

advantages of tablets vs laptop computers

1) very fast to switch on

2) fully portable

3) touch screen- simple to use, doesn't need any other input device

4) longer battery life

5) not much heat- use solid-state technology

disadvantages of tablets vs laptops

1) more expensive than laptops

2) often have limited memory or storage compared to laptop

3) typing on touch screen is slow and error-prone compared to standard keyboards

the main uses of smartphones, tablets and phablets

1) entertainment (music, videos, tv programmes)

2) used as a camera or video camera

3) sending and receiving emails

4) instant messaging

5) video calling using VoIP

6) calendar functions

7) telephone banking

artificial intelligence (AI)

development of computer systems that can perform tasks usually requiring human intelligence, such as visual perception, speech recognition and decision making

positive impacts of AI

1) enhances productivity by automating repetitive tasks

2) improves decision making through data analysis and pattern recognition

3) carries out unpleasant tasks- bomb disposal

negative impacts of AI

1) could lead to many job losses (manufacturing)

2) dependancy on technology and the inability to carry out tasks done by robots

3) loss of skills

extended reality (XR)

the term to describe technologies that can merge the physical and virtual worlds to create a fully immersive experience

features of augmented reality

1) allow user to experience the relationship between virtual and real worlds

2) virtual objects are overlaid onto real world situations

3) user is not isolated from real world and is still able to see what's going on in front of them

in the future, augmented reality will have an impact on

1) safety and rescue operations (allows the team tto interact with the environment and try out different rescue procedures before doing the real thing)

2) entertainment (film characters can be brought home)

3) shopping and retail (virtual tour of new car)

4) healthcare (understand the patients body to help in surgery and diagnosis)

features of virtual reality

1) take user out of real world into digital world

2) must wear VR headset

3) fully immersed in stimulated digital world unlike AR

in the future, virtual reality will have an impact on

1) military applications (training to operate a new tank)

2) heritage (to walk around areas like the Stonehenge)

3) sport (golfer trying to improve his swing)

4) engineering (seeing how new designs like bridges will look in existing environments)