IGCSE ICT: Types & Components of Computer Systems PDF

Chapter 1–Types and components of computer systems IGCSE - ICT Learning Objectives Define software as programs for controlling the operation of a computer of processing of electronic data Define applications software Define and describe system software and describe...

Chapter 1–Types and components of computer systems IGCSE - ICT Learning Objectives Define software as programs for controlling the operation of a computer of processing of electronic data Define applications software Define and describe system software and describe operating software which contain a command line interface (CLI) and a graphical user interface (GUI) 1.1 Hardware and software Hardware Software 1.1 Hardware and software  Computer Hardware Physical parts/components of computer system  Desktop & Laptop Desktop Laptop Has a computer case All components integrated Separate into a single, portable unit. – monitor – keyboard – mouse  Types of Computer Device Output Input Device Device Storage Processor Device  1.2 The main components of computer systems Processor = CPU Central Processing Unit What does CPU do? Complex calculation and logical decisions Executing computer programs Sends instructions to other parts of the computer CPU components ALU (Arithmetic Logic Unit) CU (Control Unit) Cache Other Hardware Components Video Card Generate images Give output to a display Other Hardware Components Sound Card Record and play back sounds Other Hardware Components Power Supply Converts AC electricity to DC Other Hardware Components Hard Disk Drive Storing programs and data The computer can read from and write to it. External Hardware Devices Software The set of instruction that controls/runs a computer system/hardware  Main Types of software 1. System software (let you manage the hardware and software resources) – Examples : Main Types of software 1. System software (System software provides the services that the computer requires to operate) Examples : Compiler Linker Device driver Utilities Interpreter Operating system  Main Types of software 1. System software (System software provides the services that the computer requires to operate) Examples : Operating system – Is a collection of programs to control and manage all of the software and hardware of the computer system. – managing the computer's resources and providing a user interface Utilities software – tools for maintaining and optimising the computer's performance System software includes the following: Compilers – Convert the program written by a human in a high-level language into code that microprocessor can understand – a series of 1s and 0s. – translating high-level programming languages into machine code Linkers – Take one or more of the files produced by the compiler and combines them into a program that the microprocessor can execute. – combining object files into a single executable program Device drivers – Part of the operating system. Device drivers allow the processor to communicate with devices such as the keyboard, mouse, monitor and printer.  Main Types of software 2. Applications software (Programs that carry out operations for specific applications. Application software is installed on top of system software, software cannot run on its own without system software) Examples:  Main Types of software 2. Applications software Application software is software chosen by a user to help them carry out a specific task. Examples: Word processing: creating and editing text documents Spreadsheet: organising and analysing data in a grid format Video editing: creating and modifying video files Graphics editing: creating and modifying images Audio editing: creating and modifying sound files Control/measurement: uses sensors to measure and control a system Computer-Aided Design (CAD): designing and modelling objects in 2D or 3D Database management systems: storing, retrieving and managing data in databases How to interact with the Operating System 1. GUI (Graphical User Interface) (It allows you to enter commands by pointing at icons or objects that appear on the screen, and then clicking on them) A Windows 10 desktop GUI How to interact with the Operating System 2. CLI (Command Line Interface) How to interact with the Operating System 2. CLI (Command Line Interface)  CLI demo Creating folders Creating files Rename a folder Rename a file Deleting a file Deleting a folder  Off-the-shelf software General purpose programs that are combined into one integrated package. Example : – Microsoft Office Software Microsoft Word Microsoft Excel Microsoft PowerPoint Custom-made software Software specially written for specific use. Example : – Payroll programs – Stock Control – Route Planning – Travel Industry – Weather Forecasting  Analogue and digital data Analogue data refers to audio or video signals and such like that vary continuously. Analogue data information represented by a quantity (e.g. an electric voltage or current). – Example human voice, animal sounds, notes played by instruments Digital data is based on binary form, information represented by certain fixed values rather than as a continuous range. – Music files, spreadsheets document, presentation documents  Analogue and digital data Digital data: discrete, fixed value (used by computers) Analogue data/signals: continuous value that varies smoothly – Analogue device = measure length, weight, temperature etc. – E.g. Thermometer – represents temp. by the height of the liquid column – Sensors: measure physical and analogue qualities  Analogue to digital conversion Analogue to Digital Converter (ADC) – Used when you want to attach an analogue input device to a digital device such as a computer. – This is so the analogue data can be understood/processed by the computer since computers only work w/digital data – E.g. When processing data sent from a sensor  Analogue and digital data Figure 1.4: Graphs showing how waves differ between different sounds  Digital to analogue conversion Digital to Analogue Converter (DAC) – Used when you want to attach an analogue output device to a digital device such as a computer – E.g. If the computer is being used to control a device (motor/valve) the device will be controlled by variable voltages; the DAC will be used to send out analogue signals  Analogue and digital data KEY WORDS Process: carry out of execute the instructions Transistor: a device that regulates current or voltage flow and acts as a switch for electronic signals Digital: information represented by certain fixed values rather than as a continuous range. Usually, data represented by the digits 1 and 0 Analogue: information represented by a quantity (e.g., an electric voltage or current) that is continuously variable. Changes in the information are indicated by changes in voltages Bit: short for binary digit, is the smallest unit of data in a computer. It has a single binary value, either 1 or 0. Sample: making a physical measurement of a wave at set time intervals and converting those measurements to digital values 1.2 The main components of computer systems The Central processing unit (CPU) The CPU is responsible for executing (running) the program instructions, processing data and controlling other computer components. It consists of the following components: the control unit (CU), the arithmetic and logic unit (ALU), the clock and the registers.  The Central Processing Unit The control unit is the component of the central processing unit (CPU) that directs the operations of the processor.  The Central Processing Unit Arithmetic and logic unit performs arithmetic and logical operations. It carries out activities such as: – Addition and subtraction – Multiplication and division – Comparisons, such as whether one number is greater than another.  The Central Processing Unit The clock is a quartz crystal. It controls the rate at which CPU works. The clock sends out a pulse to the control unit which can process one instruction for each pulse. The number of pulses per second is known as the clock speed.  The Central Processing Unit Registers are memory locations within the CPU itself. They store instructions and data that is currently being used by the control unit.  Main or Internal Memory Random Access Memory (RAM) RAM for desktop computer  Main or Internal Memory Random Access Memory (RAM) is attached to computer motherboard RAM for laptop  Main or Internal Memory Random Access Memory (RAM) – Volatile//Data is lost when the computer is turned off – Stores the current running program/instruction – RAM can be written to and read from  Main or Internal Memory Read-only memory (ROM) Don’t confuse main memory ROM with a CD- ROM or DVD-ROM; they are different  Main or Internal Memory Read-only memory (ROM)  Main or Internal Memory Read-only Memory (ROM) – Has data preinstalled onto it that cannot be removed. – It stores the start-up instructions of the computer example: BIOS – Keeps its contents when the computer is off. (non-volatile).  BIOS Basic Input Output System  Storage device A storage device is used to store programs and data when the processor is turned off. Storage devices are sometimes called backing storage, secondary storage or external storage, these all mean the same thing. Backing storage : a secondary storage device for data. External storage device : data storage that is separate from the computer, it usually plugs into a USB port on the computer. Secondary storage device : sometimes called external memory, an example would be a pen drive.  Backing Storage A secondary storage device for data Examples of backing storage : External hard disk Pen drive/Thumb drive  1.03 Operating Systems An operating system is a set of programs that controls how the computer interacts with the users and the peripherals – external devices such as keyboards, monitors and printers. Three most common Operating systems  User interfaces Users interact with the operating system through a user interface that converts what a user inputs to a form that the computer can understand and vice versa.  User interfaces Users interact with the operating system through a user interface that converts what a user inputs to a form that the computer can understand and vice versa. Four main types of user interface are : – Command line interface (CLI) – Graphical user interface (GUI) – Dialogue-based interface – Gesture-based interface  Command line interface (CLI) Interface for communicating with a computer using specific commands to tell the computer what to do. The first type of interface that was available for personal computers.  Users had to type in commands to instruct the computer.  CLIs are used by people like technicians looking after computer systems. Command line interface (CLI)  1.03 Operating Systems Description of a Command Line Interface (CLI) A way of interacting with a computer via keyboard input at a prompt on the screen. Command line interface (CLI) Advantages of a CLI: CLIs require very little processing so run very quickly and on computers that aren’t powerful. Advanced computer users who know how to use the commands can operate them faster than users who need to move a mouse. Command line interface (CLI) Disadvantages of a CLI: Commands need to be learnt and often aren’t obvious. Looks intimidating for new users. The user must be careful not to make any typing errors, otherwise the computer will not to be able to understand the commands and carry them out.  Graphical user interface (GUI) The most common type of interface used today.  Features of a graphical user interface (GUI)  Easy to use  Control the GUI with the mouse  GUIs use icons to represent things that can be done.  The screen can be divided into different areas which can have different things in them Graphical user interface (GUI) Advantages: It is intuitive as files and directories represented by icons. Users do not have to learn complicated commands. It is easy to use, for example, to move a file user just has to drag an onscreen representation (icon) of that file. Graphical user interface (GUI) Disadvantages: GUIs use up a lot of the computer internal memory to run. They are large and take up lots of storage space. They need to use the CPU a lot more than CLIs. Can be slower for experienced users as they have to take their hands of the keyboard and search for a mouse  Dialogue-based interface A dialogue-based user interface allows a user to interact with a computer through the spoken word.  Dialogue-based interfaces are common in modern cars where a user can give spoken commands to the operating system to make a phone call, switch the radio channel or plot a route to a destination. Dialogue-based interface Advantages: It allows hand-free control. The user does not have to be trained but may have to learn the necessary key words that the computer will accept. It is safer when operating machinery such driving and is useful for disabled users. Dialogue-based interface Disadvantages: Users have to learn which commands can be used Users have to train the interface with their voice May not be reliable especially if there is background noise Not suitable for the safety critical commands Complex to program and are therefore expensive  Gesture-based interface A true gesture-based interface uses computer sensors to detect and understand human gestures and movements, usually of the face and hands, without actually touching a physical device.  Partial gesture-based interfaces are available today on smartphone and tables where a user has to swipe the screen in a particular way to open and close programs and zoom in or out of maps. Gesture-based interface Advantages: The users does not have to use a mouse or other pointing device. The user does not have to enter commands using a keyboard. The user does not have to move to the device as they can make the gestures from where they are sitting or standing. The user does not have to touch a screen that others have been touching. It prevents to spread the disease. Gesture-based interface Disadvantages: Users have to learn the gestures for particular requests. A system is required to recognize face movements and hand gestures. Users may have to wear motion tracking gloves. Users may become fatigued after performing the gestures.  1.04 Types of Computer Tablets Smartphones Laptops Personal Computers / Desktop Advantages and disadvantages at page 16  1.5 Emerging technologies Emerging technologies include artificial intelligence and extended reality have a large impact on people and society.  Artificial intelligence (AI) Artificial intelligence can be applied in different fields, the one that most people recognize in the development of robotics. Artificial intelligence:  The ability of a digital computer or computer-controlled robot to perform tasks commonly associated with human intelligence such as learning, problem solving and pattern recognition.  Artificial intelligence (AI) Robots follow a fixed program and cannot learn how to do another task unless a human reprograms them. Using artificial intelligence , a computer or robot can modify its own behavior. They can learn new things without having their programs rewritten by a human. Machine learning:  The ability of computers to learn without being explicitly programmed.  Artificial intelligence (AI) Examples: Making a patient diagnosis based on their symptoms and their medical history. Autonomous machines – driverless car and lorries which can travel to a destination safely without human involvement. Virtual personal assistants also learn from your involvement with them. They can make suggestion about things you might be interested in.  Artificial intelligence (AI) Examples: Analysing test results of medical markers indicating abnormalities in patient body. Artificial intelligence allowing machines to become fully autonomous – make decisions without human involvement. Virtual personal assistants also learn from your involvement with them. They can make suggestion about things you might be interested in.  Virtual reality Artificial intelligence can be applied in different fields, the one that most people recognize in the development of robotics. Virtual reality:  A computer-generated environment, , where a person can immerse themselves and interact to perform a wide variety of actions.  Virtual reality Examples: Virtual walkthrough of a museum or the inside of a new car. VR for training astronauts, pilots or medical students before going into difficult situation. VR to create prototypes of a new vehicle so that can be tested before being developed.  Augmented reality Augmented reality allows user to interact with the real and virtual world at the same time. It superimposes a computer-generated image on a user’s view of the real world. Augmented reality:  A combined virtual and real environment Augmented reality Examples: Try the glasses virtually before you buy it. Augmented reality Examples: Augmented reality game that uses location tracking and mapping technology where players catch Pokemon characters which are superimposed on real locations.