IT111_Mod2A PDF - Introduction to Computing

Course : Introduction to Computing Module No. : 2 (Concept of Computer System) stem Title : A. Introduction to Computer Objectives: : Why are computers important? Computers have become a vital part of our everyday life. It has significantly changed the way we...

Course : Introduction to Computing Module No. : 2 (Concept of Computer System) stem Title : A. Introduction to Computer Objectives: : Why are computers important? Computers have become a vital part of our everyday life. It has significantly changed the way we live, learn, work and play. It is almost inconceivable that you could spend a day without at least one event being influenced by a computer. Perhaps the word ‘computer’ automatically conjures up the image of a personal computer sitting on a desk, but in fact it is the computers you cannot see that influence your life the most. Typical examples of common products that may use these ‘invisible’ computers are: ​ cars ​ washing machines ​ bar-code reading systems ​ DVD players/writers ​ central-heating controllers ​ microwave ovens ​ games consoles. ​ Smart televisions This is a very short extract from a very long list, but even this limited set of examples shows how significant the use of computers has become. Without computers many everyday products such as mobile phones would not exist, dramatic progress in the development of products such as artificial limbs could not have happened, and you would not have the luxury of many conveniences now taken for granted, such as email. The computers which form the basis of those used today were mainly developed in the 1940s. 1  The computer is a smart and useful machine that can do many things. It can make our work easier and faster, and can also be used for entertainment. Since computers can store a lot of information, and can do tasks very quickly and accurately, they are used in schools, banks, hospitals, shops, offices, airports, railway stations, cinemas and many other places. Some of the things we can do with a computer are: ­ We can quickly do mathematical operations. ­We can create essays and reports. ­We can draw and colour pictures. ­We can listen to music or watch films. COMPUTER ORGANIZATION A computer system consists of mainly four basic units; namely input unit, storage unit, central processing unit and output unit. Central processing unit further includes: Arithmetic Logic Unit (ALU) and Control Unit. A computer performs five major operations or functions irrespective of its size and make. These are: It accepts data or instructions as input; It stores data and instruction; It processes data as per the instructions; It controls all operations inside a computer; and It gives results in the form of output. 2 Functional Units that Makes Computers Work: a. Input Unit: This unit is used for entering data and programs into the computer system by the user for processing. Figure 1: Basic Computer Organization b. Storage Unit: The storage unit is used for storing data and instructions before and after processing. c. Output Unit: The output unit is used for storing the result as output produced by the computer after processing. d. Processing: The task of performing operations like arithmetic and logical operations is called processing. The Central Processing Unit (CPU) takes data 3  and instructions from the storage unit and makes all sorts of calculations based on the instructions given and the type of data provided. It is then sent back to the storage unit. CPU includes Arithmetic Logic Unit (ALU) and Control Unit (CU). Arithmetic Logic Unit: All calculations and comparisons, based on the instructions provided, are carried out within the ALU. It performs arithmetic functions like addition, subtraction, multiplication, division and also logical operations like greater than, less than and equal to etc. Control Unit: Controlling of all the operations like input, processing and output are performed by control unit. It takes care of step by step processing of all operations inside the computer. Memory Computer’s memory can be classified into two types: primary memory and secondary memory. a. Primary Memory can be classified as RAM and ROM RAM or Random Access Memory is the unit in a computer system. It is the place in a computer where the operating system, application programs and the data in current use are kept temporarily so that they can be accessed by the computer’s processor. It is said to be ‘volatile’ since its contents are accessible only as long as the computer is on. The contents of RAM are no more available one the computer is turned off. ROM or Read Only Memory is a special type of memory which can only be read and contents of which are not lost even when the computer is switched off. It typically contains manufacturer’s instructions. Among other things, ROM also stores an initial program called the ‘bootstrap loader’ whose function is to start the operation of computer system once the power is turned on. b. Secondary Memory RAM is volatile memory having a limited storage capacity. Secondary/auxiliary memory is storage other than the RAM. These include devices that are peripheral and are connected and controlled by the computer to enable permanent storage of programs and data. Hard Disk 4  Hard disks are made up of rigid material and are usually a stack of metal disks sealed in a box. The hard disk and the hard disk drive exist together as a unit and is a permanent part of the computer where data and programs are saved. These disks have storage capacities ranging from 1GB to 80GB and more. Hard disks are rewritable. Compact Disk Compact Disk (CD) is portable disk having data storage capacity between 650-700 MB. It can hold large amount of information such as music, full-motion videos, and text etc. CDs can either be read only or read write type. Digital Video Disk (DVD) Digital Video Disk (DVD) is similar to a CD but has larger storage capacity and enormous clarity. Depending upon the disk type it can store several Gigabytes of data. DVDs are primarily used to store music or movies and can be played back on your television or the computer too. UNIT OF MEASUREMENT Storage Measurements The basic unit used in computer data storage is called a bit (binary digit). Computers use these little bits, which are composed of ones and zeros, to do things and talk to other computers. All your files, for instance, are kept in the computer as binary files and translated into words and pictures by the software (which is also ones and zeros). This two number system is called “binary number system” since it has only two numbers in it. The decimal number system in contrast has ten unique digits, zero through nine. Table 1. Computer Storage Unit UNIT ABBREVIATION 1 OR 0 Kilobyte KB 1024 bytes Megabyte MB 1024 kilobytes Gigabyte GB 1024 megabytes Terabyte TB 1024 gigabyte Speed Measurement 5 The speed of Central Processing Unit (CPU) is measured by Hertz (Hz), which represents a CPU cycle. The speed of the CPU is known as the computer speed. Table 2. Computer Speed Measurement 1 hertz or Hz 1 cycle per second 1 MHz 1 million cycles per second or 1000 Hz 1 GHz 1 billion cycles per second or 1000 MHz CATEGORIES OF COMPUTERS Industry experts typically classify computers in seven categories: personal computers (desktop), mobile computers and mobile devices, game consoles, servers, mainframes, supercomputers, and embedded computers. A computer’s size, speed, processing power, and price determine the category it best fits. Due to rapidly changing technology, however, the distinction among categories is not always clear-cut. This trend of computers and devices with technologies that overlap, called convergence, leads to computer manufacturers continually releasing newer models that include similar functionality and features. For example, newer cell phones often include media player, camera, and Web browsing capabilities. As devices converge, users need fewer devices for the functionality that they require. When consumers replaced outdated computers and devices, they should dispose of them properly. Categories of Computers Personal Computers A personal computer is a computer that can perform all of its input, processing, output, and storage activities by itself. A personal computer contains a processor, memory, and one or more input, output, and storage devices. Two popular architectures of personal computers are the PC and the Apple. The term, PC-compatible refers to any personal computer based on the original IBM personal computer design. Companies such as Dell, HP, and Toshiba sell PC-compatible computers. PC and PC-compatible computers usually use a Windows operating system. Apple computers usually use Macintosh operating system. Two types of personal computers are desktop computers and notebook computers. 6  Desktop Computers A desktop computer is designed so that the system unit, input devices, and any other devices fit entirely on or under a desk or a table. In many models, the system unit is a tall and narrow tower, which can sit on the floor vertically – if desktop space is limited. Some desktop computers function as a server on a network. Others, such as gaming desktop computer and home theater PC, target a specific audience. The gaming desktop computer offers high-quality audio, video, and graphics with optimal performance for sophisticated single—user and networked or Internet multiplayer games. A home theater PC (HTPC) combines the features of a high-definition video/audio entertainment system with a desktop computer that is designed to be connected to a television and includes a Blu-ray Disc, digital video recorder, and digital cable television connectivity. These high-end computers cost more than the basic desktop computer. Another expensive, powerful desktop computer is the workstation, which is geared for work that requires intense calculations and graphics capabilities. An architect uses a workstation to design buildings and homes. A graphic artist uses a workstation to create a computer-animated special effects for full-length motion pictures and video games. Mobile Computers and Mobile Devices A mobile computer is a personal computer you can carry from place to place. Similarly, a mobile device is a computing device small enough to hold in your hand. 7 Notebook Computers A notebook computer, also called a laptop computer, is a portable, personal computer often designed to fit on your lap. Notebook computers are thin and lightweight, yet they can be as powerful as the average desktop computer. A notebook, which is a type of notebook computer, is smaller, lighter, and often not as powerful as a traditional notebook computer. An ultra-thin is another type of notebook computer that is lightweight and usually less than one-inch thick. Some notebook computers have touch screen, allowing you to interact with the device by touching the screen usually with the tip of a finger to be able to run the application programs and also browse on the internet. These computers weigh on average from 2.5 to more than 10 pounds (depending on the configuration), which allows users to transport the computers from place to place. Most notebook computers can operate on batteries or a power supply or both. Tablet PCs Resembling a letter-sized slate, a Tablet PC, or tablet computer, is a special type of notebook computer that you can interact with by touching the screen with your finger or a digital pen. A digital pen looks like a small ink pen but uses pressure instead of ink. Users write or draw on a table PC by pressing a finger or digital pen on the screen, and issue instructions by tapping on the screen. One design of Table PC, called a convertible table, has an attached keyboard. Another design, which does not include a keyboard, is called a slate tablet and 8 provides other means for typing. Some tablet PCs also support voice input so that users can speak into the computer. Tablet PCs are useful especially for taking notes in lectures, at meetings, conferences, and other forums where the standard notebook computer is not practical. Mobile Devices Mobile devices, which are small enough to carry in a pocket, usually do not have disk drives. Instead, these devices store programs and data permanently on special memory inside the system unit or on a small storage media such as memory cards. You often can connect a mobile device to a personal computer to exchange information between the computer and the mobile device. Some mobile devices are internet-enabled, meaning they can connect to the Internet wirelessly. With an Internet-enabled device, users can chat, send e-mail and instant messages, and access the Web. Because of their reduced size, the screens on mobile devices are small, but usually are in color. Popular types of mobile devices are smart phones and PDAs, e-book readers, handheld computers, portable media players, and digital cameras. 9 Smartphones and PDAs Offering the convenience of one-handed operation, a smartphone is an Internet-enabled phone that usually also provide personal information management functions such as a calendar, an appointment book, an address book, a calculator, and a notepad. In addition to basic phone capabilities, a smartphone allows you to send and receive e-mail messages and access the Web – usually for an additional fee. Some smartphones communicate wirelessly with other devices or computers. Many also function as a portable media player and include built-in digital cameras so that you can share photos or videos with others as soon as you capture the image. Many smartphones also offer a variety of application software such as word processing, spreadsheet, and games, and the capability of conducting live video conferences. Many smartphones have keypads that contain both numbers and letters so that you can use the same keypad to dial phone numbers and enter messages. Others have a built-in mini keyboard on the front of the phone or keyboard that slides in and out from behind the phone. Some have touch screens, where you press objects on the screen to make selections and enter text through an on-screen keyboard. Others include a stylus, which is similar to a digital pen but smaller and has less functionality. Instead of calling someone’s smartphone or cell phone, users often send messages to others by pressing buttons on their phone’s keypad, keys on the mini keyboard, or images on an on-screen keyboard. Types of messages users 10 send with smart phones include text messages, instant messages, picture messages, and video messages. A text message is a short note, typically fewer than 300 characters, sent to or from a smart phone or other mobile device. An instant message is a real-time Internet communications, where you exchange messages with other connected users. A picture message is a photo or other image, sometimes along with sound and text, sent to or from a smartphone or other mobile device. A phone that can send picture messages often is called a camera phone. A video message is a short video clip, usually about 30 seconds, sent to or from a smartphone or other mobile device. A phone that can send video messages often is called a video phone. A PDA (personal digital assistant), which often looks like a smartphone, provides personal information management functions such as calendar, an appointment book, an address book, a calculator, and a notepad. A PDA differs from a smartphone in that it usually does not provide phone capabilities and may not be Internet enabled, support voice input, have a built-in camera, or function as a portable media player. As smartphones and PDAs continue a trend of convergence, it is becoming increasingly difficult to differentiate between the two devices. This has led some manufacturers to refer to PDAs and smartphones simply as handhelds. E-Book Readers An e-book reader (short for electronic book reader), or e-reader, is a handheld device that is used primarily for reading e-books. An e-book, or digital book, is an electronic version of printed book, readable on computers and other digital devices. In addition to books, users typically can purchase and read other forms of digital media such as newspapers and magazines. 11 Most e-book readers have a touch screen and are Internet-enabled. These devices usually are smaller than tablet computers but larger than smartphones. Handheld Computers A handheld computer, sometimes referred to as an Ultra-Mobile PC (UMPC), is a computer small enough to fit in one hand. Many handheld computers communicate wirelessly with other devices or computers and also include a digital pen or stylus for input. Some handheld computers have miniature or specialized keyboards. Many handheld computers are industry-specific and serve the needs of mobile employees, such as meter readers and parcel delivery people, whose job require them to move from place to place. Portable Media Players A portable media player is a mobile device on which you can store, organize, and play digital media. For example, you can listen to music; watch videos, movies, and television shows; and view photos on the device’s screen. With 12 most, you download the digital media from a computer to the portable media player or to media that you insert in the device. Some portable media players are Internet-enabled so that you can access Web sites and send e-mail messages directly from the device. Many offer personal information management functions such as a calendar and address book, and include a variety of games and other application software. Portable media players usually include a set of ear buds, which are small speakers that rest inside each ear canal. Some portable media players have a touch screen, while others have a touch-sensitive pad that you operate with a thumb or finger, to navigate through digital media, adjust volume, and customize settings. Digital Cameras A digital camera is a device that allows users to take pictures and store the photographed images digitally, instead of traditional film. While many digital cameras look like a traditional camera, some are built into smartphones and other mobile devices. 13  Although digital cameras usually have some amount of internal storage to hold images, most users store images on a small storage media such as memory cards. Digital cameras typically allow users to review, and sometimes modify, images while they are in the camera. Some digital cameras connect to or communicate wirelessly with a computer or printer, allowing users to print or view images directly from the printer. Some memory cards can connect to a network wirelessly, so that they can transfer photos directly from the memory card in the camera to the Internet without requiring a computer. Often users prefer to download images from the digital camera to the computer. Or, you can remove the storage media such as memory card from the digital camera and insert it in a card reader in or attached to the computer. Game Consoles A game console is a mobile computing device designed for single-player or multiplayer video games. Standard game consoles use a handheld controller(s) as an input device(s); a television screen as an output device; and hard disks, optical discs, and/or memory card for storage. Weighing on average between two and nine pounds, the compact size of game consoles makes them easy to use at home in the car, in a hotel, or any location that has an electrical outlet. 14 A handheld game console is small enough to fit in one hand, making it more portable than any game console. With the handheld game console, the controls, screen, and speakers are built into the device. Because of their reduced size, the screen are small – three to four inches. Some models use cartridges to store games; others use a memory card or a miniature optical disc. Many handheld game consoles can communication wirelessly with other similar consoles for multiplayer gaming. In addition to gaming, many game console models allow users to listen to music, watch movies, keep fit, and connect to the Internet. 15  Servers A server control access to the hardware, software, and other resources on a network and provides a centralized storage area for programs, data, and information. Servers can support from two to several thousand connected computers at the same time. In many cases, one server access data, information, and programs on another server. In other cases, people use personal computers or terminals to access data, information, and programs on a server. A terminal is a device with monitor, keyboard, and memory. 16  Mainframes A mainframe is a large, expensive, powerful computer that can handle hundreds or thousands of connected users simultaneously. Mainframes store tremendous amounts of data, instructions, and information. Most major corporations use mainframes for business activities. With mainframes, enterprises are able to bill millions of customers, prepare payroll for thousands of employees, and manage thousands of items in inventory. One study reported that mainframes process more than 83 percent of transactions around the world. Mainframes also can act as servers in a network environment. Servers and other mainframes can access data and information from a mainframe. People can also access programs on a mainframe using terminals or personal computers. 17  Supercomputers A supercomputer is the fastest, most powerful computer – and the most expensive. The fastest supercomputers are capable of processing more than one quadrillion instructions in a single second. With weights that exceeds 100 tons, these computers can store more than 20,000 times the data and information of an average desktop computer. Applications requiring complex, sophisticated mathematical calculations use supercomputers. Large-scale simulations and applications in medicine, aerospace, automotive design, online banking, weather forecasting, nuclear energy research, and petroleum exploration use a supercomputer. Embedded computers An embedded computer is a special-purpose computer that functions as a component in a larger product. Embedded computers are everywhere – at home, in your car, and at work. Few Embedded Computer examples are Raspberry Pi, Beagle Bone, Arduino YUN, FPGa, Beagle Bone etc.The following list identifies a variety of everyday products that contain embedded computers. 18  o Consumer Electronics: mobile and digital telephones, digital televisions, cameras, video recorders, DVD players and recorders, answering machines. o Home Automation Devices: thermostats, sprinkling systems, security monitoring systems, appliances, lights o Automobiles: antilock brakes, engine control modules, airbag controller, cruise control o Process Controllers and Robotics: remote monitoring system, power monitors, machine controllers, medical devices o Computer Devices and Office Machines: keyboards, printers, fax and copy machines Because embedded computers are components in larger products, they usually are small and have limited hardware. These computers perform various functions, depending on the requirements of the product in which they reside. Embedded computers in printers, monitor the amount of paper in the tray, check the ink or toner level, signal if a paper jam has occurred, and so on. 19  An Embedded Computer is a small-sized, compact, powerful and easy-to-operate electronic module, based on microcontroller/microprocessor and act as a bridge between electronics hardware and computer software. Embedded Computer performs specific functionality, which is normally programmed in it by its programmer. DATA AND INFORMATION Computers process data into information. Data is a collection of unprocessed items, which can include text, numbers, images, audio, and video. Information conveys meaning and is useful to people. Many daily activities with involve the use of or depend on information from a computer. For example, computers process several data items to print information in the form of cash register receipts. INFORMATION PROCESSING CYCLE Computers process data (input) into information (output). Computers carry out processes using instructions, which are the steps that tell the computer how to perform a particular task. A collection of related instructions organized for a common purpose is referred to as software. A computer often holds data, information, and instructions in storage for future use. Some people refer to the series of input, process, output, and storage activities as the information processing cycle. Most computers today communicate with other computers. As a result, communications also has become an essential element of information processing cycle. ADVANTAGES AND DISADVANTAGES OF USING COMPUTERS Society has reaped many benefits from using computers. A user is anyone who communicates with a computer or utilizes the information it generates. Both business and home users can make well-informed decisions because they have instant access to information from anywhere in the world. Students, another type of user, have more tools to assist them in the learning process. 20 Advantages of Using Computers Benefits from using computers are possible because computers have the advantages of speed, reliability, consistency, storage, and communications. Speed: When the data, instructions, and information flow along electronic circuits in a computer, they travel at incredibly fasts speeds. Many computers process billions or trillions of operations in a single second. Processing involves computing (e.g. adding, subtracting), sorting (e.g. alphabetizing), organizing, displaying images, recording audio, playing music, and showing a movie or video. Reliability: The electronic components in modern computers are dependable and reliable because they rarely break or fail. Consistency: Given the same input and process, a computer will produce the same results – consistently. A computing phrase - known as garbage in, garbage out – points out that the accuracy of a computer’s output depends on the accuracy of the input. Storage: A computer can transfer data quickly from storage to memory, process it, and then store it again for future use. Many computers store enormous amounts of data and make this data available for processing anytime it is needed. Communications: Most computers today can communicate with other computers, often wirelessly. Computers with this capability can share any of the four information processing cycle operations – input, process, output, and storage – with another computer or a user. Disadvantages of Using Computers Some disadvantages of computers relate to health risks, the violation of privacy, public safety, the impact on the labor force, and the impact on the environment. Health Risks: Prolonged or improper computer use can lead injuries or disorders of the hands, wrists, elbows, eyes, neck, and back. Computer users can protect themselves from these health risks through proper workplace design, good posture while at the computer and appropriately spaced work breaks. Two behavioral health risks are computer are computer addiction and technology overload. Computer addiction occurs when someone becomes obsessed with using a computer. Individuals suffering from technology overload feel distressed when deprived of computers and mobile devices. Once recognized, both computer addiction and technology overload are treatable disorders. Violation of Privacy: Nearly every life event is stored in a computer somewhere... in medical records, credit reports, tax records, etc. In many instances, where 21  personal and confidential records were not protected properly, individuals have found their privacy violated and identities stolen. Public Safety: Adults, teens, and children around the world are using computers to share publicly their photos, videos, journals, music, and other personal information. Some of these unsuspecting, innocent computer users have fallen victims to crimes committed by dangerous strangers. Protect yourself and your dependents from these criminals by being cautious in e-mail messages and on Web sites. Impact on Labor Force: Although computers have improved productivity in many ways and created an entire industry with hundreds of thousands of new jobs, the skills of millions of employees have been replaced by computers. Thus, it is crucial that workers keep their education up-to-date. A separate impact on the labor force is that some companies are outsourcing jobs to foreign countries instead of keeping their homeland labor force employed. Impact on Environment: Computer manufacturing processes and computer waste are depleting natural resources and polluting the environment. When computers are discarded in landfills, they can release toxic materials and potentially dangerous levels of lead, mercury, and flame retardants. Green computing involves reducing the electricity consumed and environmental waste generated when using a computer. Strategies that support green computing include recycling, regulating manufacturing processes, extending the life of computers, and immediately donating or properly disposing of replaced computers. When you purchase a new computer some retailers offer to dispose of your old computers properly. 22