What is a computer Types of computers Computer Peripherals Role of Computers & ICT in development

A computer is an electronic device which accepts and processes data by following a set of instructions (Program) to produce a result (Information). Since the ultimate aim of a computer is to produce information, computing is often referred to as INFORMATION PROCESSING

Computers can be classified mainly in three different ways. These are: By processing power By purpose By nature of data processed

Classification by Processing Power: These include: Microcomputers Servers Minicomputers Mainframes Supercomputers

Supercomputers Mainframes Minicomputers Servers Microcomputer

The most powerful and most expensive computers. Designed for extremely fast processing speeds Have fewer terminals and processors are superior to all other types of computers Used for complex mathematical calculations such as those needed in scientific research or space exploration.

Have many terminals and several disk tape drives. Their components have greater storage capacity and are faster than those of minicomputers. They can process numerous programs concurrently Can be used by medium to large sized businesses for their data processing needs For example the network support for Automated Teller Machines (ATMs).

They are medium-sized computers that usually have several terminals for input and output, several disk drives and sometimes tape drives for data storage. Have greater storage capacity and speed compared to microcomputers Often process several programs at once Can be used by several people simultaneously Small and medium-sized businesses use minicomputers for their data processing needs

These are high-end microcomputers They are recommended for carrying out game development, scientific calculations, engineering or 3D graphics It is faster than the common personal computer Can be used to set up a network client.

These are built to be used by one person They are commonly called Personal Computers or PC. User can surf the web, play games and music, type and edit text and many other tasks. These are common in homes, schools, hospitals etc They possess a single microprocessor from which they get their name.

Input Storage /Retrieval Computer Processing Output

Input: refers to the process of physically or automatically adding data into a computer system Implies giving commands for data to be processed by a given computer application installed on the computer Is done by the use of INPUT DEVICES

Processing: The manipulation of digitized data which includes conversion of raw data into useful information. Implies changing raw meaningless facts into useful format that can be applied to solve problems. Is done by the CENTRAL PROCESSING UNIT.

Output: refers to any information that has been processed by and sent out of a computer or similar device. It may come in various forms such as: Audio Video Hard Copy Soft Copy 3 Dimension or 3D Output is produced from a computer system through devices called OUTPUT DEVICES

Storage/Retrieval: this refers to the systematic process of collecting and cataloging information so that they can be located and displayed on request. Storage of information on a computer system is done either permanently or temporarily. Storage is also called MEMORY. Storage of information is done by STORAGE DEVICES These devices can either be internal or external

INPUT AND OUTPUT DEVICES

INPUT PERIPHERALS OR DEVICES Peripherals are devices that are connected to the computer box or Central Processing Unit (CPU).

TYPES OF PERIPHERALS Input devices these are devices that pass data into the computer system. Output devices these are devices that pass information out of the computer system Backing storage devices these are deices that store programs and data.

INPUT DEVICE This is the hardware or device used to enter or transfer data into the computer system. It is categorised into Manual input devices & Automatic/Automated input devices.

MANUAL INPUT DEVICES

MANUAL INPUT DEVICE: This is a type of control device that requires an individual to manually press a button OR this is the entry of data by hand into a device at the time of processing

EXAMPLES OF MANUAL INPUT DEVICES

MOUSE Mouse: is an input device that controls the movement of the cursor or pointer on the display screen.

EXAMPLES OF MICE

TRACKERBALL Is an input device that looks like an upside down mouse. The pointer is moved by rotating the ball using a thumb or finger.

EXAMPLES OF TRACKER BALL

JOYSTICK An input device that looks similar to a control device that is used for playing games. A joystick allows an individual to move an object in a game such as navigating a plane in a flight simulator.

EXAMPLES OF JOYSTICKS

LIGHT PEN A light pen is a lightsensitive pointing device commonly used to select or modify text or data on a screen.

EXAMPLES OF LIGHT PENS

KEYPAD Keypad is a small and special keyboard with fewer keys or buttons used in special dedicated devices. it consists of digits, symbols and/or alphabetical letters which can be used to enter data. For example, calculator, cell phone, remote control etc.

EXAMPLES OF KEYPADS

MICROPHONE Microphone: is an input device used to send audio into the computer system. OR is an input device that allows a user to speak to the computer to enter data and instructions into the computer system.

EXAMPLES OF MICROPHONES

KEYBOARD Keyboard : is an input device used mainly for typing text into the computer system.

The keyboard has keys for letters and numbers. The following are the main parts of a keyboard: The function keys, The numeric keypad (number pad), navigation keys (arrow keys), QWERTY or Alphanumeric Keys.

PARTS OF THE KEYBOARD (i) Function keys (F1 to F12) The Function keys found on the top row, perform different functions or tasks depending on which program someone is using. Example in a word processor (Ms Word) F7 key is used for spell checking, F1 is used for help etc

(ii) Numeric Keypad or Number pad The numeric keypad, located on the right side of most keyboards, allows you to enter numbers quickly. Although not available on laptops.

(iii) Arrow keys or Navigation keys The navigation keys, such as the four directional arrow keys allow you to move the cursor and position within a document or webpage.

(iv) Alphanumeric or QWERTY pad This has keys for letters, numbers and special keys Ctrl (Control), Shift, Alt, Fn, Alt Gr, Caps lock, : ; %,&, $, @,?, #, Window button, Pg(Page) down, Pg(Page)Up, Del(Delete), Enter, Esc(Escape), Home, Tab, Pause break, Prt Sc(Print Screen), End, Back space, Space Bar,

Wrist pad This is a plastic wrist pad which supports the users wrists and relieve stress found from typing on a keyboard.

EXAMPLES OF KEYBOARDS

EXAMPLES OF INPUT DEVICES

CONCEPT KEYBOARD This is the type of keyboard where pictures represent some item of data and is sometimes used in fast food restaurants, supermarkets on tills.

EXAMPLES OF CONCEPT KEYBOARDS

REPETITIVE STRAIN INJURY (RSI) This is when a user uses a keyboard or mouse over and over and damages the nerves of the hands, wrists.

GRAPHIC TABLET Graphic Tablet/Drawing tablet: This is a highly accurate hardware input device that is used for drawing or sketching. e.g. an artist drawing

EXAMPLES GRAPHIC TABLET

DIGITAL CAMERA Digital Camera: is an input device that stores the pictures and videos in electronic format.

EXAMPLES OF DIGITAL CAMERAS

TOUCH SCREEN Touch screen: This is a device which is both an input and output. It is a special screen that allow a user to choose options by touching images.

EXAMPLES OF TOUCH SCREENS

AUTOMATIC OR AUTOMATED INPUT DEVICES

AUTOMATIC INPUT DEVICE: This is a type of control device that automatically control each step in a process.

EXAMPLES OF AUTOMATIC OR AUTOMATED DEVICES

SCANNER Scanner: This is a device that captures printed material, text, images into the computer and convert it into a digital file.

EXAMPLES OF SCANNERS

BARCODE READER Barcode Reader: is a device that uses lightbeam to read and interpret bar codes in the computer. E.g. Point Of Sale (POS)

EXAMPLES OF BARCODE READERS

WEBCAM / WEB CAMERA Web Cam or Web Camera: is a small camera connected to a computer used to capture and transmit audio and video over the Internet.

EXAMPLES OF WEB CAM OR WEB CAMERAS

OPTICAL CHARACTER READER/RECOGNITION (OCR) OCR: is the device that process text or letters and converting them into data that a computer can interpret.

EXAMPLES OF OPTICAL CHARACTER READER/RECOGNITION (OCR)

OPTICAL MARK READER / RECOGNITION (OMR) OMR: is a device that detects the presence of pencil marks made on a piece of paper or document. E.g. marking grade 7 multiple questions exams.

EXAMPLES OF OPTICAL MARK READERS/RECOGNITION

MAGNETIC INK CHARACTER READER/RECOGNITION (MICR) MICR: is a device that is used in the bank for reading paper cheques.

EXAMPLES OF MAGNETIC INK CHARACTER READER /RECOGNITION

EXAMPLES OF MAGNETIC INK CHARACTER READER / RECOGNITION (MICR)

Infrared detectors useful in burglar alarm systems to detect body heat. Pressure sensors also in burglar alarm systems and many control applications.

Light sensors can be used in microprocessor-controlled cameras to adjust exposure. Card readers cards such as credit cards have a data encoded in a magnetic strip. Others such as satellite viewing cards are called smart cards and have more data stored in a microchip.

OUTPUT DEVICES

OUTPUT DEVICE This is the device that pass processed information or results to the user. Two types of output are hard copy (printed output) and softcopy (visual or sound/audio).

Soft-copy: This is output information displayed visually on a VDU/ screen/monitor or in audio form. Audio output: is output from the speaker/loudspeaker Hard-copy: This is a permanent paper printed by a printer.

EXAMPLES OF OUTPUT DEVICES

MONITOR/VISUAL DISPLAY UNIT(VDU)/SCREEN This is an output device that displays signals on a computer screen. It is used to view images and documents.

There are different types of computer monitors such as the Cathode Ray Tubes (CRT), Liquid Crystal Display (LCD), Thin Film Transistor (TFT- LCD) and the Light Emitting Diodes (LED).

EXAMPLES OF CATHODE RAY TUBES (CRT) MONITORS

EXAMPLES OF LIQUID CRYSTAL DISPLAY (LCD) MONITOR

EXAMPLE OF LIGHT EMITTING DIODE (LED) MONITOR

PRINTER Printer: This is an output device that prints text or graphics on paper.

TYPES OF PRINTERS Below are some of the examples of printers: Laser Printer, Ink Jet Printer Dot Matrix Printer

LASER PRINTER Laser Printer: This is an output device that prints high-quality resolution text and graphics by means that is similar to photocopying.

EXAMPLES OF LASER JET PRINTERS

INKJET PRINTER Inkjet Printer: This is an output device that prints by spraying ink on paper. It is mostly used at home

EXAMPLES OF INKJET PRINTERS

DOT MATRIX PRINTER Dot Matrix Printer: it is an output device that print images that are made up of a number of individual dots.

EXAMPLES OF DOT MATRIX PRINTERS

MOTORS: These are found on computer control devices such as robots or paint spraying machinery, electric motors.

PLOTTER Plotter: is a special output device that prints, draws, produce high quality graphical images on very large pieces of paper. E.g. Computer Aided Design (CAD), Architect and technical drawings (drawings of buildings and maps). Types of plotters are drum plotters, flatbed plotters etc.

EXAMPLES OF PLOTTERS

LCD PROJECTOR LCD PROJECTOR: An output device that can display and project large images from the computer system.

EXAMPLES LCD PROJECTORS OR BEAMERS

SPEAKERS SPEAKER: This is an output device which is sometimes connected to the computer to give out beeping signals and audio sounds.

EXAMPLES OF SPEAKERS

HEADPHONES Headphones: are output devices with a pair of small loudspeakers that are placed over the head, for listening to audio signals such as music or speech.

EXAMPLES OF HEADPHONES