Introduction to Computer System PDF

Chapter 1 INTRODUCTION TO COMPUTER SYSTEM Lecture 1.0 OBJECTIVES After studying this chapter you will be able to: Learn the concept of a system in general and the computer system in specific. Learn and understand how the computers have evolved dramatically within a very sho...

Chapter 1 INTRODUCTION TO COMPUTER SYSTEM Lecture 1.0 OBJECTIVES After studying this chapter you will be able to: Learn the concept of a system in general and the computer system in specific. Learn and understand how the computers have evolved dramatically within a very short span, from very huge machines of the past, to very compact designs of the present with tremendous advances in technology. Understand the general classifications of computers. Study computer applications. Understand the typical characteristics of computers which are speed, accuracy, efficiency, storage capacity, versatility. Understand limitations of the computer. Discuss the similarities and differences between the human and the computer. Understand the Component of the computer. 1.1 INTRODUCTION- Computer  Today, almost all of us in the world make use of computers in one way or the other. applications in various fields of engineering, medicine, commercial, research and others. also in our daily lives, in all the devices that we use daily like cars, games, washing machines, microwaves etc. in day to day computations like banking, reservations, electronic mails, internet and many more. 1.1 INTRODUCTION- Computer The word computer is derived from the word compute. The computer was originally defined as a super fast calculator. It had the capacity to solve complex arithmetic and scientific problems at very high speed. In addition, nowadays computers perform many other tasks like accepting, sorting, selecting, moving, comparing various types of information. 1.2. Computer As Data Processor 1.2.1. Computer As Data Processor Data is raw, unorganized facts that need to be processed. Data can be something simple and seemingly random and useless until it is organized.  Information : When data is processed, organized, structured or presented in a given context so as to make it useful, it is called information. Information actually consists of data that has been organized to help answers questions and to solve problems Computer As Data Processor 1.2.2.The Information Processing Cycle  Using all its parts together, a computer converts data into information by per forming various actions on the data. For example, a computer might perform a mathematical operation on two numbers, then display the result. Or the computer might perform a logical operation such as comparing two numbers, then display that result. These operations are part o f a process called the information processing cycle, which is a set of steps the computer follows to receive data, process the data according to instructions from a program, display the resulting information to the user, and store the results 1.2.2.The Information Processing Cycle 1.2.2.The Information Processing Cycle information processing cycle has four parts, and each part involves one or more specific components of the computer: » Input. During this part of the cycle, the computer accepts data from some source, such as the user or a program, for processing. » Processing. During this part of the cycle, the computer’s processing components perform actions on the data, based on instructions » Output. Here, the computer may be required to display from the user or a program. the results of its processing. For example, the results may appear as text, numbers, or a graphic on the computer’s screen or as sounds from its speaker. The computer also can send output to a printer or transfer the output to another computer through a network or the Internet. Output is an optional step in the information processing cycle but may be ordered by the user or program. » Storage. In this step, the computer permanently stores the results o f its processing on a disk, tape, or some other kind of storage medium. As with out put, storage is optional  and may not always be required by the user or program. 1.2.3. Computer As Data Processor The set of instructions given to the computer to perform various operations is called as the computer program. The process of converting the input data into the required output form with the help of the computer program is called as data processing. The computers are therefore also referred to as data processors Therefore a computer can now be defined as a fast and accurate data processing system that accepts data, performs various operations on the data, has the capability to store the data and produce the results on the basis of detailed step by step instructions given to it.. Hardware and Software The terms hardware and software are almost always used in connection with the computer. The Hardware: The hardware is the machinery itself. It is made up of the physical parts or devices of the computer system like the electronic Integrated Circuits (ICs), magnetic storage media and other mechanical devices like input devices, output devices etc. All these various hardware are linked together to form an effective functional unit. The various types of hardware used in the computers, has evolved from vacuum tubes of the first generation to Ultra Large Scale Integrated Circuits of the present generation. Hardware and Software The Software: The computer hardware itself is not capable of doing anything on its own. It has to be given explicit instructions to perform the specific task. The computer program is the one which controls the processing activities of the computer. The computer thus functions according to the instructions written in the program. Software mainly consists of these computer programs, procedures and other documentation used in the operation of a computer system. Software is a collection of programs which utilize and enhance the capability of the hardware 1.3. Classification of Computers 1.3. Classification of Computers Computers are broadly classified into two categories depending upon the logic used in their design as: 1. Analog computers: In analog computers, data is recognized as a continuous measurement of a physical property like voltage, speed, pressure etc. Readings on a dial or graphs are obtained as the output, ex. Voltage, temperature; pressure can be measured in this way. 1.3. Classification of Computers 2. Digital Computers: These are high speed electronic devices. These devices are programmable.  They process data by way of mathematical calculations, comparison, sorting etc. They accept input and produce output as discrete signals representing high (on) or low (off) voltage state of electricity. Numbers, alphabets, symbols are all represented as a series of 1s and Os. Digital Computers are further classified as General Purpose Digital Computers and Special Purpose Digital Computers. General Purpose computers can be used for any applications like accounts, payroll, data processing etc. Special purpose computers are used for a specific job like those used in automobiles, microwaves etc. 1.3. Classification of Computers Another classification of digital computers is done on the basis of their capacity to access memory and size like: A. Small Computers: I) Microcomputers: Microcomputers are generally referred to as Personal Computers (PCs). They have Smallest memory and less power. They are widely used in day to day applications like office automation, and professional applications, ex. PC- AT, Pentium etc. 1.3. Classification of Computers II) Note Book and Laptop Computers: These are portable in nature and are battery operated. Storage devices like CDs, floppies etc. and output devices like printers can be connected to these computers. Notebook computers are smaller in physical size than lap top computers. However, both have powerful processors, support graphics, and can accept mouse driven input. 1.3. Classification of Computers III)HandHeld Computers: These types of computers are mainly used in applications like collection of field data. They are even smaller than the note book computers. B. Hybrid Computers: Hybrid Computers are a combination of Analog and Digital computers. They combine the speed of analog computers and accuracy of digital computers. They are mostly used in specialized applications where the input data is in an analog form i.e. measurement. This is converted into digital form for further processing. The computers accept data from sensors and produce output using conventional input/output devices. 1.3. Classification of Computers C. Mini Computers: Mini computers are more powerful than the micro computers. They have higher memory capacity and more storage capacity with higher speeds. These computers are mainly used in process control systems. They are mainly used in applications D. like payrolls, financial accounting, Computer aided design etc. ex. VAX, PDP-11 Mainframe Computers: Main frame computers are very large computers which process data at very high speeds of the order of several million instructions per second. They can be linked into a network with smaller computers, micro computers and with each other. They are typically used in large organizations, government departments etc. ex. IBM4381, CDC E. Super Computers: A super computer is the fastest, most powerful and most expensive computer which is used for complex tasks that require a lot of computational power. Super computers have multiple processors which process multiple instructions at the same time. This is known as parallel processing. These computers are widely used in very advanced applications like weather forecasting, processing geological data etc. ex. CRAY-2, NEC - 500, PARAM. Oral Bonus Question How important are computers to our society? People often talk in fantastic terms about computers and their impact  on our lives. You probably have heard or read expressions such as “ computers have changed our world** or “ computers have changed the way we do everything” many times. Such statements may strike you as exaggerations, and sometimes they are. But if you stop and really think about the effect computers have had on our daily lives, you still may be astonished.