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1.Introduction to Computer I. INTRODUCTION TO COMPUTERS & WINDOWS I.1 DEFINITION OF COMPUTER A computer is an electronic device or a tool which accepts data1 or information2 in one form and processes it to produce data or information in another form i.e. in a more meaningful manner. It accepts data as its input, process data according to the predefined rules (programs3) and supplies results(output) in the form of data and/or actions. It can convert data into information that is useful to people. In other words a computer is a machine which collects, stores, retrieves, manipulates and transmits information. A complete computer system includes four distinct parts: Hardware Software Data User Hardware: •A computer's hardware consists of electronic devices; the parts you can see and touch. It consists of its processors, its storages, its input/output devices and its communication connections (i.e. the actual machinery: wires, transistors and circuits. ) •The term "device" refers to any piece of hardware used by the computer, such as a keyboard, monitor, modem, mouse, etc. 1 Data is a collection of basic facts (symbols that represent facts, objects, and ideas) e.g. name, age, salary etc. 2 Information is the data, which is processed into meaningful form 3 A program is a set of instructions which are written in a computer language to perform certain tasks. 1 Software: •Software – general term used to describe all the various programs – consists of organized sets of instructions for operating the computer system.•Some programs exist for the computer's use, to help it manage its own tasks and devices; These operations may include identifying, accessing and processing information.•Other programs exist for the user, and enable the computer to perform tasks for you, such as creating documents. Data: •Data consists of raw facts, which the computer can manipulate and process into information that is useful to people. •Computerized data is digital, meaning that it has been reduced to digits, or numbers. The computer stores and reads all data as numbers. •Although computers use data in digital form, they convert data into forms that people can understand, such as text, numerals, sounds, and images. 2 Users: •People are the computer's operators, or users. • Some types of computers can operate without much intervention from people, but personal computers are designed specifically for use by people. I.2 TYPES OF COMPUTERS Computers can be generally classified by size and power as follows, though there is a considerable overlap: Supercomputers •Supercomputers are the most powerful computers. They are used for problems requiring complex calculations. An extremely faster computer that can perform hundreds of millions of instructions per second. •Because of their size and expense, supercomputers are relatively rare.•Supercomputers are used by universities, government agencies, and large businesses. Mainframe computers •Mainframe computers can support hundreds or thousands of users simultaneously, handling massive amounts of input, output, and storage.•Mainframe computers are used in large organizations where many users need access to shared data and programs.•Mainframes are also used as e-commerce servers, handling transactions over the Internet. In the early days of computing, mainframes were huge computers that could fill an entire room or even a whole floor! As the size of computers has diminished while the power has increased, the term mainframe has fallen out of use in favor of enterprise server. 3 Minicomputers •Minicomputers are smaller than mainframes but larger than microcomputers. • Minicomputers usually have multiple terminals4. Minicomputers are multiprocessing systems capable of supporting from 4 to about 200 users simultaneously. • Minicomputers may be used as network servers and Internet servers. Minicomputers are normally referred to as mid-range servers now. Multiprocessing: 1) Refers to a computer system’s ability to support more than one process (program) at the same time. 2) Refers to the utilization of multiple CPUs in a single computer system. This is also called parallel processing. Workstations •Workstations are powerful single-user computers.•Workstations are used for tasks that require a great deal of number- crunching power, such as product design and computer animation.•Workstations are often used as network and Internet servers. The leading manufacturers of workstations are Sun Microsystems, Hewlett–Packard Company, Silicon Graphics Incorporated and Compaq. 4 A terminal is a device with a monitor and a keyboard. Some terminals have no processing power and must connect to a server to operate. Others have the capability of functioning when not connected to the server. 4 Microcomputers, or Personal Computers •Microcomputers are more commonly known as personal computers (PC). The term "PC" is applied to IBM-PCs or compatible computers. The personal computer (PC) defines a computer designed for general use by a single person. PCs were first known as microcomputers because they were a complete computer but built on a smaller scale than the huge systems in use by most businesses. Full-size desktop computers are the most common type of PC. •Notebook (laptop) computers are used by people who need the power of a desktop system, but also portability. They integrate the display, keyboard, a pointing device or trackball, processor, memory and hard drive all in a battery-operated package slightly larger than an average hardcover book. • Handheld PCs (such as PDAs: personal digital assistants also known as Palmtop) lack the power of a desktop or notebook PC, but offer features for users who need limited functions and small size. Palmtops are tightly integrated computers that often use flash memory instead of a hard drive for storage. These computers usually do not have keyboards but rely on touchscreen technology for user input. Palmtops are typically smaller than a paperback novel, very lightweight with a reasonable battery life. A slightly larger and heavier version of the palmtop is the handheld computer. •Wearable Computers - The latest trend in computing is wearable computers. Essentially, common computer applications (e-mail, database, multimedia, calendar/scheduler) are integrated into watches, cell phones, visors and even clothing! Examples of Computer Usage We use computers in our daily lives. At home, PC is used for business (e.g. word processing), personal Information manager, personal finance, online banking, tax preparation, E-mail, instant massaging, and chat rooms, entertainment (e.g. music composition, greeting cards), education ,etc. At work (small office/Home Office), PC can be used for business, company specific (e.g. accounting, legal reference), network management, web browser, etc. As a mobile user, you can use a portable computer for business, e-mail etc. In large Business, they use PCs connected to minicomputers, for business, accounting, network management, web browser, E-mail, etc. 5 In big industries, computers are used in a wide variety of tasks such as desktop publishing, computer aided design (CAD); with workstations connected to mainframes or minicomputers; etc. I.3 ADVANTAGES/DISADVANTAGES OF COMPUTERS a. Advantages of Using Computers in Information Processing Some advantages of using computers in information processing include Speed: Tasks can be completed faster because computers work at amazing speed. Typically more than 500,000 instructions can be processed each second. Accuracy: Computers can process large amounts of data and generate error-free results, provided that the data is entered correctly Storage & Retrieval: Computers can store enormous amounts of data for future use. Data stored in computers is readily available and can be accessed at very high speeds. Automation: Due to its ability to follow a set of instruction; tasks can be completed with little human intervention (i.e. automatic). Low cost: Though initial investment may seemingly be high, running and maintenance costs become lower in the long term. High volumes: Due to speed to execution and storage facilities the computer is ideal for jobs of high volume. Repetitive Operations: In situations where identical operations have to be performed on sets of data e.g. for Payroll the computer follows the same set of instructions at fast speeds having error free results. The high reliability of components inside modern computers enables computers to produce consistent results. Efficiency and productivity can be raised. Overall security can be raised due to less human intervention. Customer services can be improved due to more efficiently management and operations. Computers with communicating capability can share data and information with other computers. b. Disadvantages of using computers for information processing include Unemployment: Some jobs may be lost due to computerization and thus lower the morale of staff members. Face-to-face interactions among staff may be reduced. It needs trained people: Some staff has to be trained or retrained Expensive: - Initial investment cost can be high. - Extra cost is required to employ specialized staff to operate and design the data processing system. I.4 BLOCK STRUCTURE OF COMPUTERS & FUNCTION OF COMPONENTS All general purpose computers require the following hardware components: OUTPUT DEVICES CPU INPUT DEVICES Figure: Components of a computer 6 A computer's hardware devices are categorized as follows: •Processor •Memory •Input and output (I/O) devices •Storage devices Central Processing Unit (CPU):
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