A mind is like a parachute. It doesn't work if it is not open. : A mind is like a parachute. It doesn't work if it is not open. Types and components of Computer Systems : Types and components of Computer Systems Information and Communication Technology Candidates should be able to : Candidates should be able to define hardware, giving examples
define software, giving examples
describe the difference between hardware and software
identify the main components of a general-purpose computer: central processing unit, main/internal memory (including ROM and RAM), input devices, output devices and secondary/backing storage
identify operating systems, including those which contain a graphical user interface, a command line Interface
identify different types of computer including Personal Computer or desktop, mainframe, laptop, palmtop and Personal Digital Assistant
describe recent developments in ICT 3 CIE 0417 IGCSE ICT Unit-1 INTRODUCTION TO THE COMPUTER : INTRODUCTION TO THE COMPUTER The term computer is used for any device that may be employed to compute or to calculate. 4 CIE 0417 IGCSE ICT Unit-1 What is Computer? : What is Computer? A computer is an electronic device that receives input, stores it for a period of time, operating it according to a set of instructions (Known as a PROGRAM) and gives the user with an output.
Computer is an electronic device which converts data into information. 5 CIE 0417 IGCSE ICT Unit-1 Types of Computers : Types of Computers Computers come in all sorts of shapes and sizes. Based on Capacity, speed and reliability computers can be divided into the following categories of computers:
PC/desktop computers usually refers to a general purpose computer which is made up of separate monitor, keyboard, mouse and processor unit. 6 CIE 0417 IGCSE ICT Unit-1 Types of Computers : Types of Computers Laptop (or Notebook) refers to a type of computer where the monitor, keyboard, pointing device and processor are all together in one single unit. This makes them extremely portable systems.
The key features of a laptop are:
Low weight (to aid portability)
Low power consumption (and also long battery life)
a processor that does not generate too much heat ( cooling is very important) 7 CIE 0417 IGCSE ICT Unit-1 Types of Computers : Types of Computers Netbook is a term used to describe a computer that can almost fit onto a hand and is a smaller version of a laptop. These used to be known as palmtop computers, but this term now generally applies to much smaller devices which use touch screen and often a stylus to key in data.
Netbooks don’t have optical drives. 8 CIE 0417 IGCSE ICT Unit-1 Types of Computers : Types of Computers Personal digital assistants (PDAs) are small handheld computers that usually come with a touch screen that is activated using a stylus. Data is entered by using a keyboard that appears on the touch screen. PDAs now have basic database, word-processing and spreadsheet facilities. 9 CIE 0417 IGCSE ICT Unit-1 Types of Computers : Types of Computers Mainframe computers is a term used for a large, very powerful computer system.
Their main purpose is to run commercial applications such as banking and insurance, where huge amounts of data need to be processed each day.
Fast processor speeds
Multiple Operating Systems
Huge RAM 10 CIE 0417 IGCSE ICT Unit-1 Computer System : Computer System A computer system is the combination of hardware and software. A typical computer system has memory and set of states that define the relationship between the system's inputs and outputs. 11 CIE 0417 IGCSE ICT Unit-1 Important Terms : Important Terms DATA- The collection of raw facts is called data. Without knowing the context (what the data actually represents) the data is just a meaningless collection of values.
PROCESSING- The action required to be performed on data to convert it into result is called processing. 12 CIE 0417 IGCSE ICT Unit-1 Important Terms : Important Terms RESULT- The useful information after processing of data is called result.
INFORMATION- It is the collection of data according to a set parameter. With context, data is information. 13 CIE 0417 IGCSE ICT Unit-1 Important Terms : Important Terms INPUT- The process of collecting and entering data into the computer is called input.
OUTPUT- Output is the result we get after the processing of data and taking it out of memory. 14 CIE 0417 IGCSE ICT Unit-1 Important Terms : Important Terms SYSTEM- A system is a group of interrelated components (Here Hardware and Software) that collectively achieve a desired result. 15 CIE 0417 IGCSE ICT Unit-1 FEATURES OF COMPUTER : FEATURES OF COMPUTER Speed
Diligence 16 CIE 0417 IGCSE ICT Unit-1 LIMITATIONS OF A COMPUTER : LIMITATIONS OF A COMPUTER Computer is as intelligent as is the program that runs it. Without a program computer is useless.
Computer cannot detect wrong feeding of data. 17 CIE 0417 IGCSE ICT Unit-1 Simple Input/Output System : Simple Input/Output System INPUT PROCESS OUTPUT Input Unit is used to enter data into Computer Processing takes place in the processing unit. It has three main units-Memory, CU, ALU. We get the output on the output unit. 18 CIE 0417 IGCSE ICT Unit-1 The Architecture of a Computer : The Architecture of a Computer 19 CIE 0417 IGCSE ICT Unit-1 Flow of Information : Flow of Information The parts are connected to one another by a collection of wires called a bus. 20 CIE 0417 IGCSE ICT Unit-1 Computer Components : Computer Components The Computer System has two main components which when both combined makes a computer system. These are
Software 21 CIE 0417 IGCSE ICT Unit-1 : Hardware
Hardware means the physical structure of a computer, i.e., the parts that can be touched by us. All the components attached to the computer like Keyboard, Mouse, Monitor, Printers are hardware. An correlation…….
Your hardware is all of the parts that make up your body: bones, muscles, skin, blood, etc. 22 CIE 0417 IGCSE ICT Unit-1 : Software
Hardware is just a box with electronic parts in it. It cannot do any work by itself. It needs certain programs to do some work. Software is a general term used to describe a collection of instructions. These instructions tell the computer what to do. To continue the correlation……..
Your software is all of your thoughts and mental processes: these are the instructions that tell your physical body what to do 23 CIE 0417 IGCSE ICT Unit-1 The Difference Between Hardware and Software : The Difference Between Hardware and Software Computer hardware is the physical components that make up the computer system. Hardware is useless without software to run on it.
Software is instructions that tell computer hardware what to do. Software is useless unless there is hardware to run it on. 24 CIE 0417 IGCSE ICT Unit-1 The Difference Between Hardware and Software : The Difference Between Hardware and Software For a computer system to be useful it has to consist of both hardware and software. Remember: Hardware is the actual components that your computer is made of: ram, rom, motherboard, modem, wireless chip etc. Software is any program that you load onto a computer: the operating system (Windows, Linux) games or applications. Completing the correlation…………
Your physical body cannot function without your thoughts.
And your thoughts need a physical body to exist within 25 CIE 0417 IGCSE ICT Unit-1 Hardware Components : Hardware Components We can categorize hardware components in three broad categories:
CPU, the Central Processing Unit, and
[Backing] Storage Devices or Secondary Memory 26 CIE 0417 IGCSE ICT Unit-1 Input Unit : Input Unit An input unit is a device through which data and programs from the outside world are entered into the computer
Keyboard, the mouse, and scanning devices 27 CIE 0417 IGCSE ICT Unit-1 Central Processing Unit : Central Processing Unit CPU stands for Central Processing Unit.It is a small chip inside the computer. It does all decisions, calculations. It also controls other parts of a computer. CPU consists of several section:
Control Unit (CU)
Arithmetic and Logic Unit (ALU)
Main Memory Each of the section has its own function. They work together with other Peripherals to form a computer. 28 CIE 0417 IGCSE ICT Unit-1 1. Control Unit : 1. Control Unit Control Unit controls operations of other parts of CPU as well as all parts of computer by sending a control signal, e.g.
control sequence of instruction to be executed
control flow of data among all parts of computer
regulate timing of processor
send control single to and receive control single from peripheral devices The control unit of the CPU contains circuitry that uses electrical signals to direct the entire computer system to carry out, or execute, stored program instructions. Like an orchestra leader, the control unit does not execute program instructions; rather, it directs other parts of the system to do so. The control unit must communicate with both the arithmetic/logic unit and memory. 29 CIE 0417 IGCSE ICT Unit-1 2. Arithmetic and Logic Unit : 2. Arithmetic and Logic Unit Arithmetic and Logic Unit consists of a complicated set of logic circuit and accumulator. It is mainly responsible for
Logical comparison and decision 30 CIE 0417 IGCSE ICT Unit-1 3. Main Memory : 3. Main Memory Memory is a collection of cells, each with a unique physical address
The size of a cell is normally a power of 2, typically a byte.
A cell is the smallest addressable unit of memory – i.e. one cell can be read from memory or one cell can be written into memory, but nothing smaller.
Each cell has an address, starting at 0 and increasing by 1 for each cell.
A cell with a low address is just as accessible as one with a high address- hence the name RAM.
The width of the cell determines how many bits can be read or written in one machine operation. 31 CIE 0417 IGCSE ICT Unit-1 : The main memory holds the program instructions and data. It contains two types of memory chip, called ROM and RAM.
Random Access Memory (RAM) is the part of the computer that temporarily stores the instructions that the computer is running, and the data it is processing. RAM is a volatile storage device. When a computer is in use, its RAM will contain…
The operating system software
The application software currently being used
Any data that is being processed 32 CIE 0417 IGCSE ICT Unit-1 : Read-Only Memory (ROM) is used in most computers to hold a small, special piece of software: the 'boot up' program. This software runs when the computer is switched on or 'boots up'. The software checks the computer’s hardware and then loads the operating system.
RAM is volatile, ROM is not: This means that RAM does not retain its bit configuration when the power is turned off, but ROM does 33 CIE 0417 IGCSE ICT Unit-1 Output Unit : Output Unit An output unit is a device through which results stored in the computer memory are made available to the outside world
Printers and video display terminals 34 CIE 0417 IGCSE ICT Unit-1 Storage Devices : Storage Devices Secondary or backing storage is used to store programs and data when they are not being used i.e. used to store permanently. Secondary storage is non-volatile, so data that is stored on these devices remains there safely.
A hard drive, a CD-ROM, a floppy disc and a USB memory stick are all examples of secondary storage devices. 35 CIE 0417 IGCSE ICT Unit-1 Magnetic Tape : 36 Magnetic Tape The first truly mass auxiliary storage device was the magnetic tape drive CIE 0417 IGCSE ICT Unit-1 Magnetic Disks : 37 Magnetic Disks A read/write head travels across a spinning magnetic disk, retrieving or recording data CIE 0417 IGCSE ICT Unit-1 Compact Disks : 38 Compact Disks A CD drive uses a laser to read information stored optically on a plastic disk
CD-ROM is Read-Only Memory
DVD stands for Digital Versatile Disk CIE 0417 IGCSE ICT Unit-1 Peripheral Devices : Peripheral Devices Peripheral devices are not part of the central core of the computer. The general name for extra/additional devices is ‘peripheral devices’. They are usually categorized into input devices, output devices and storage devices.
CD-ROM drive, Mouse, Printer, Speaker, Scanner, Zip drive are some examples of peripheral devices. 39 CIE 0417 IGCSE ICT Unit-1 Types of Software : Types of Software Application Software
Utility Software 40 CIE 0417 IGCSE ICT Unit-1 : System Software
A system software package is a collection of programs designed to operate, control, and extend processing capabilities of computers.
Operating System is one of the system software. 41 CIE 0417 IGCSE ICT Unit-1 : Application Software
An application software is a set of programs that allow computer to perform a specific data-processing job for the user.
Special Purpose Software
General Purpose Software 42 CIE 0417 IGCSE ICT Unit-1 : Utility Software
Utility software is special purpose software that improves the operations of system software by providing additional and specialized functionality to it. It helps to keep your system in shape by eliminating/correcting error. Utility is a program that performs a very specific task, usually related to managing system resources. 43 CIE 0417 IGCSE ICT Unit-1 Operating Systems : Operating Systems An Operating System is the most important program that runs on a computer. Every general-purpose computer must have an operating system to run other programs. Operating systems perform basic tasks, such as recognizing input from the keyboard, sending output to the display screen, keeping track of files and directories on the disk, and controlling peripheral devices such as disk drives and printers. 44 CIE 0417 IGCSE ICT Unit-1 Operating Systems : Operating Systems Operating systems provide a software platform on top of which other programs, called application programs, can run. The application programs must be written to run on top of a particular operating system. Your choice of operating system, therefore, determines to a great extent the applications you can run. The platform defines a standard around which a system can be developed. 45 CIE 0417 IGCSE ICT Unit-1 Operating Systems : Operating Systems In any computer, the operating system:
controls the backing store and peripherals such as scanners and printers
deals with the transfer of programs in and out of memory
organizes the use of memory between programs
organizes processing time between programs and users
maintains security and access rights of users
deals with errors and user instructions
allows the user to save files to a backing store The platform defines a standard around which a system can be developed. 46 CIE 0417 IGCSE ICT Unit-1 User Interfaces : User Interfaces A user interface is the method by which the user and the computer exchange information and instructions. There are two main types:
Command Line or Character User Interface (CUI)
Graphical User Interface (GUI) 47 CIE 0417 IGCSE ICT Unit-1 User Interfaces : User Interfaces Command-line interfaces
A command-line interface allows the user to interact with the computer by typing in commands-set of instruction. The computer displays a prompt, the user keys in the command and presses enter or return. An example of a common command driven interface is MS-DOS.
Features of a command-line interface
Commands must be typed correctly and in the right order or the command will not work.
Experienced users who know the commands can work very quickly without having to find their way around menus.
An inexperienced user can sometimes find a command driven program difficult to use because of the number of commands that have to be learnt. 48 CIE 0417 IGCSE ICT Unit-1 User Interfaces : User Interfaces Graphical user interfaces
Graphical user interface is sometimes shortened to GUI. The user chooses an option usually by pointing a mouse at an icon representing that option.
Features of GUIs include:
They are much easier to use for beginners.
They enable you to easily exchange information between software using cut and paste or 'drag and drop'.
They use a lot of memory and processing power. 49 CIE 0417 IGCSE ICT Unit-1 User Interfaces : User Interfaces When discussing user interfaces, it is important to note that Windows XP, Windows Vista, Apple OSX and Ubuntu all have graphical user interfaces.
Windows XP: an operating system by Microsoft
Windows 7: an operating system by Microsoft
Windows Vista: an operating system by Microsoft
Apple OSX: an operating system by Apple Computers
Ubuntu: an open source (freely available) operating system Simply, a GUI is a one where the Operating System uses a WIMP- Windows Icons Menus Pointers environment. 50 CIE 0417 IGCSE ICT Unit-1 Points to Remember : Points to Remember The speed of a CPU is measured in Hertz (Hz). The speed generally corresponds to the number of actions the CPU can perform every second.1 Megahertz (MHz) is 1,000,000 (1 million) Hertz
1 Gigahertz (GHz) is 1,000,000,000 (1 billion) Hertz
A typical, modern, fast CPU runs at around 2.8GHz. That means it can perform almost 3 billion actions every second! 51 CIE 0417 IGCSE ICT Unit-1