2+-+Computer+Systems.pptx.pdf

INTRODUCTION TO COMPUTER SYSTEMS  A COMPUTER is a programmable electronic device that processes data based on a set of instructions given by the user or a program. A computer may be in the form of a desktop or laptop or much more simple device like a calculator. – a calculator wil...

INTRODUCTION TO COMPUTER SYSTEMS  A COMPUTER is a programmable electronic device that processes data based on a set of instructions given by the user or a program. A computer may be in the form of a desktop or laptop or much more simple device like a calculator. – a calculator will accept two numbers 6 and 10 (input) and add them (process) and display the result ‘16’ (output) Can you think of any other devices that can be considered a computer?  The computer never works alone. It is always a part of a system known as the computer system. The COMPUTER SYSTEM is a collection of devices and programs that work together with the computer to process data. The main purpose of a computer system is to process raw facts and figures, known as data, into meaningful information which can be output or stored for use in the future. This processing happens in three stages: Input Processing Output  THE COMPUTER SYSTEM To process data to produce information, a computer needs both hardware and software. HARDWARE SOFTWARE Hardware is all the parts of the computer Software is a set of instructions that a system that you can see and feel. computer needs to carry out its tasks.  COMPUTER HARDWARE Computer hardware can be classified into four groups based on their purpose: INPUT PROCESSING OUTPUT STORAGE Input devices are used The processor is known Output devices convert Storage refers to any to get data and as the ‘brain’ of the information processed media or device that a instructions into the computer because this by the computer into a computer uses to keep computer for is where the data is human-readable form. data instructions processing. turned into information. available for immediate or later use.  INPUT HARDWARE INPUT Input is any data or instruction that is entered into the computer system. Within the computer system, there are specialized devices that can be used to enter data into the computer system. These are known as INPUT DEVICES. For example: Keyboard Mouse Can you think of any other device you have used to input data into your computer?  scanner keyboard stylus microphone mouse Track ball Barcode scanner joystick Touch screen INPUT DEVICES Input devices are divided into three categories based on how they deliver data to the computer system. 1. Key input 2. Point and Draw 3. Source Data Automation KEY INPUT DEVICE Key input devices have keys which are used to enter data into a computer. The keyboard is the only key input device. A keyboard has rows of keys which are pressed to input alphanumeric characters or carry out a particular function of the computer. POINT AND DRAW DEVICES Point and Draw devices are used to point to, select or click a particular object or text on the computer screen. They can also be used to draw. Examples: Mouse Touch screen/Digitizer Joystick Touch pad Trackball Stylus POINT AND DRAW DEVICES MOUSE The mouse is a handheld pointing device that is used to control the movement of the onscreen pointer and cursor. It allows you to point to, select or manipulate objects on the screen. JOYSTICK The joystick consists of a vertical handle mounted on a base unit with several buttons. There are sensors in the base unit which translate the motion of the vertical handle so that the computer can understand. These are popular in computer gaming. TRACKBALL This trackball is mounted in a stable base and is used to control the movement of the on screen cursor or pointer. The ball has numerous sensors which track its movement and can be more accurate than a mouse. POINT AND DRAW DEVICES STYLUS The stylus is a small pen-like device used to enter data by reacting to a touch-sensitive screen or film. These are commonly used with tablets and other touch screen devices. TOUCH SCREEN/DIGITIZER A touch screen receives input based on the movement of your finger (or a stylus) on its surface. These finger movements provide input for the computer system which control its operations. TOUCH PAD A touch pad is a rectangular surface across which you can drag your finger to control the pointer on a computer. These are commonly found in laptop computers. SOURCE DATA AUTOMATION DEVICES Source data automation devices input audio, video or source document(s) directly into the computer in a machine-readable format without the use of the keyboard or mouse. Examples: Scanner Magnetic Ink Character Reader Barcode reader Magnetic Strip Reader Digital camera Optical Mark Reader Microphone Optical Character Reader SOURCE DATA AUTOMATION DEVICES SCANNER A scanner is a device that uses light to read an image or text and turn it into a digital format. The digital data can then be saved as an image or document file. BARCODE READER A bar code is a series of stripes of varying thickness which represent a sequence of numbers that the computer reads as data. The barcode reader uses an optical scanner to read the code and converts it into electrical pulses which are input into the computer. MICROPHONE The microphone inputs sound which is converted into a digital form the computer can understand. DIGITAL CAMERA Cameras capture images or records videos digitally. SOURCE DATA AUTOMATION DEVICES MAGNETIC STRIPE READER A magnetic stripe reader is designed to read the information stored within the magnetic stripe of special cards such as credit cards. The information stored on the black magnetic stripe is transferred to the computer when the card is swiped through the reader. OPTICAL MARK READER (OMR) Optical mark readers read pencil or pen marks made in pre-defined positions on paper. Light is directed onto the paper and the reflected light is analyzed. If little light is reflected back to the OMR, that means that there is a mark on the surface of the paper. This device is used to mark multiple choice answers. SOURCE DATA AUTOMATION DEVICES OPTICAL CHARACTER READER (OCR) An optical character reader is used for scanning printed documents into digital versions. It detects shape and identifies characters then matches them against a set of patterns stored in the computer. MAGNETIC INK CHARACTER READER (MICR) Magnetic ink character recognition is a technology that utilizes special characters printed in magnetized ink. When a document (most times a bank cheque) goes through the machine the ink produces a current, and the pattern of the current indicates which characters are present. This pattern is input into the computer system. The MICR is used in the banking industry. Identify the each of the following input devices and the category they belong to: PROCESSING HARDWARE THE CENTRAL PROCESSING UNIT (CPU) The processing takes place in the part of the computer called the CENTRAL PROCESSING UNIT. The CPU: is considered the brain of the computer takes the raw data and turns it into information. performs all calculations and coordinates all activities The processor is housed on the motherboard. DATA vs. INFORMATION The main job of the CPU is to convert data into information. DATA - raw, unorganized, facts and figures that must be processed by the computer INFORMATION - data that has been processed and now has meaning. Information includes the data plus its context (the reason the data was collected) For example, if you have a collection of ages of students in class, that list would be considered data because it does not have any meaning. To give this data meaning, you might add a title to the list like “Ages of students in 1-5” or use the numbers to create a graph or chart. CENTRAL PROCESSING UNIT (CPU) The speed at which the data is processed in the CPU is called processing speed and gives an idea of how powerful the processor is. Processing speed in measured in Megahertz (MHz) or Gigahertz (GHz). The higher the number of MHz or GHz, the faster the processing speed. The CPU is made up of three smaller units: Control Unit Arithmetic and Logic Unit Registers  The CONTROL UNIT is the main part of the CPU. All input is first sent to the CU which then decides which part of the computer the data should be sent to be processed. Once the data is finished processing, it is sent back to the control unit. The ARITHMETIC and LOGIC UNIT performs all arithmetic and logic functions in a computer. If an instruction involves addition, subtraction, multiplication or division or the comparison of data, the CU sends this data is sent to the ALU for processing. Some of the logic functions include: ‘equal to’, ‘less than’, ‘greater than or equal to’, ‘not equal to’ etc. REGISTERS are high speed storage locations that temporarily hold data and instructions that are being processed by the central processing unit. EXAMPLES OF PROCESSORS  OUTPUT HARDWARE Output Hardware Output devices display the information processed by the computer that is in a form the user can understand. Output can be presented in four ways: 1. Text 2. Graphics 3. Audio 4. Video CATEGORIES OF OUTPUT HARD COPY OUTPUT SOFT COPY OUTPUT ▪ Output printed on paper or on ▪ Output displayed on a screen or another permanent, tangible form by other non-permanent, of media. intabgible means – For example: A Word document – For example: content displayed on a printed on a sheet of paper monitor ▪ This type of output is retained ▪ Unless the information is stored in even when the computer is turned the computer system, soft copy off. output is lost when the computer is turned off. Can you categorize the following devices as either hard copy or soft copy output devices? Can you categorize the following devices as either hard copy or soft copy output devices? HARD COPY OUTPUT SOFT COPY OUTPUT HARD COPY OUTPUT DEVICES ▪ Printers are the most common hard copy output devices. They can be divided into two categories based on their method of printing. – IMPACT PRINTER: produces output by striking a ribbon with a hammer and creating a mark on the paper behind the ribbon. – NON-IMPACT PRINTER: produces output via heat, ink or laser which do not require any ribbon or paper to be struck. IMPACT PRINTERS Line Printer ▪ The line printer has a continuous feed of paper and prints an entire line of text before moving to another line. ▪ They are normally used in businesses when high volumes of output are required. ▪ Line printers are fast and have a low operating cost. ▪ Line printers cannot produce graphics. IMPACT PRINTERS Dot Matrix Printer ▪ This printer forms images one character at a time as the print head moves back-and-forth or in an up-and-down motion on the page. ▪ The print head has pins which strike an ink-coated ribbon and forces the ribbon to contact the paper so that the pin makes a small dot on the paper. ▪ This type of printer is slow, noisy, and produces low quality output. ▪ They are cheap and have a low operating cost. IMPACT PRINTERS Daisy Wheel Printer ▪ The print mechanism in this printer looks like a daisy and at the end of each ‘petal’ is a fully formed character. When the hammer strikes the ‘petal’ a character is printed on the paper ▪ Print speeds are very low but the quality of output is relatively good. NON-IMPACT PRINTERS Laser Printer ▪ A laser is used to outline the text/image with electrostatically charged dots on a light sensitive drum which attracts the toner powder. Once the powder is transferred to the paper, it is fixed to the paper by applying heat. ▪ The laser printer is fast, quiet and produces crisp, high quality output. ▪ These are often used in offices or schools. NON-IMPACT PRINTERS Ink Jet Printer ▪ An ink jet printer produces output by squirting tiny jets of ink at the paper being printed on. A column of ink jets in the print head moves across the page and squirts dots onto the paper to print the desired output. ▪ The inkjet produces good quality output but the quality is not as high as laser printers. ▪ The printers are commonly used at home by families or individuals. ▪ Replacing ink cartridges for this printer can be expensive. NON-IMPACT PRINTERS Thermal Printer ▪ A thermal printer prints on special heat sensitive paper that has a dye special dye coating. When the paper is heated, the dye turns black and the output is revealed. ▪ Thermal printers are not costly to operate, are portable and quiet. ▪ These printers are typically found in retail stores.  PLOTTER ▪ A plotter is a printer that interprets commands from a computer to make large line drawings such as blueprints on paper with automated pens. ▪ These devices are especially used for architectural and engineering drawings. ▪ Plotters are more expensive than other types of printers.  SOFT COPY OUTPUT DEVICES ▪ Monitor – This output device displays whatever tasks is being done on its screen. There are two popular types of screens – Cathode Ray Tube and Liquid Crystal Display (LCD) – The monitor is the most common output device and it is the main output device in most computer systems. – Monitors are also known as visual display units (VDUs)  SOFT COPY OUTPUT DEVICES ▪ Projector – This is an output device that takes an image or (moving images) generated by the computer and projects them onto a surface or larger screen for viewing. ▪ Speakers/Headphones – These are output devices which connect to a computer’s sound card and outputs sounds generated by the computer  STORAGE HARDWARE Storage Hardware When data is processed by the computer, it can be stored, presented as output or both. A storage device is any type of hardware that stores data or information for immediate or later usage. Storage devices can be divided into two categories: 1. PRIMARY STORAGE 2. SECONDARY STORAGE PRIMARY STORAGE ▪ Primary storage refers to memory used to store data and instructions that are to be manipulated and executed by the CPU. ▪ Primary storage is also known as main memory or internal memory. ▪ Primary storage only stores data and instructions being used by the computer while it is running. Once the power is off, the data is lost. As a result, primary storage is considered volatile. RANDOM ACCESS MEMORY (RAM) ▪ Random access memory is the most common type of memory found in computers. ▪ It temporarily holds data and information that your computer is actively using so that it can be accessed quickly. ▪ RAM is volatile so when the computer is switched off, all the contents of RAM are lost. READ-ONLY MEMORY (ROM) ▪ Read only memory is computer memory which stored data permanently or semi-permanently. Unlike RAM, the contents of ROM will remain stored even after your computer is turned off. ▪ The information stored in ROM is usually pre-installed by the manufacturer and contains utility programs such as disk management programs or boot up instructions. ▪ Traditionally, ROM was read-only meaning its contents could not be changed but newer versions of ROM allow some rewriting/upgrading.  SECONDARY STORAGE ▪ Secondary storage refers to memory that is used to store information over the long-term. It is also referred to as auxiliary storage. ▪ It is non-volatile which means that the information stored is not lost when the computer is switched off. ▪ There are three types of secondary storage: 1. MAGNETIC STORAGE 2. OPTICAL STORAGE 3. SOLID STATE STORAGE  MAGNETIC STORAGE ▪ Magnetic storage devices typically use different patterns of magnetization on a material that is able to be magnetized such as a disk or tape to store data. The patterns represent binary data and can be read using read/write heads which can recognize and/or change the magnetization patterns. ▪ Examples include: Floppy disk Hard disk drive Magnetic tape Zip disk drive  OPTICAL STORAGE ▪ Optical storage devices are discs made from metal and plastic. The data is stored on the surface of these disks which have flat areas and hollow areas. ▪ A laser is used to scan the surfaces of these devices. When the laser shines, the light is either reflected back or scattered based on the flat or hollow of the discs surface. These patterns of reflection represent binary data. ▪ Examples include: – Compact discs (CD) – Digital Versatile disc (DVD) – Blu-Ray disc (BD)  SOLID STATE STORAGE ▪ Solid state storage devices store data electronically in silicon microchips. Due to a special technology known as flash memory, solid state storage devices are able to retain their information in the absence of electricity. ▪ Solid state storage devices do not have any moving parts which makes these devices more portable and produce less heat when compared to magnetic and optical storage. ▪ Examples include: – USB flash drive – Memory or Secure Digital (SD) cards Now, let’s compare PRIMARY and SECONDARY storage PRIMARY STORAGE SECONDARY STORAGE Price Volatility Temporary/Permanent Method of data storage Limited/unlimited storage Speed (to access data) Located on motherboard? Now, let’s compare PRIMARY and SECONDARY storage PRIMARY STORAGE SECONDARY STORAGE Price Expensive More affordable Volatile (RAM) and non-volatile Volatility Non-volatile (ROM) Temporary/Permanent Temporary and Permanent Permanent Method of data storage Electronically Magnetically, optically, electronically Limited/unlimited Limited Almost unlimited storage Speed (to access data) Very fast Slower Located on Yes, mounted directly on No, connected to motherboard? motherboard motherboard by cables