Basics of Computer PDF

# Unit I Basics of Computer ## Introduction to Computer ### Contents: * Digital and Analog Computers * Characteristics of Computer: * Speed * Accuracy * Diligence * Storage Capability * Versatility * History of Computer: * Calculating Machines: * Abacus * Na...

# Unit I Basics of Computer ## Introduction to Computer ### Contents: * Digital and Analog Computers * Characteristics of Computer: * Speed * Accuracy * Diligence * Storage Capability * Versatility * History of Computer: * Calculating Machines: * Abacus * Napier's Bones * Slide Rule * Pascal's Adding and Subtraction Machine * Leibniz's Multiplication and Dividing Machine * Punch Card System * Generations of Computers: * First Generation (1940 to 1956): Using Vacuum Tubes * Second Generation (1956 to 1963): Using Transistors * Third Generation (1964 to 1971): Using Integrated Circuits * Fourth Generation (1971 to present): Using Microprocessors * Fifth Generation (present and next): Using Artificial Intelligence * Classification of Computer: * Microcomputers: * Desktop or Personal Computer (PC) * Notebook Computers or Laptop * Netbook * Tablet Computer * Handheld Computer or Personal digital Assistant (PDA) * Smart Phones * Minicomputers * Mainframe Computers * Supercomputers * The Computer System: * Hardware * Software * Data * Users * The Input-Process-Output Concept ### Why This Chapter? Computers are an integral part of our lives. They are used for the reservation of tickets for airplanes and railways, payment of telephone and electricity bills, deposit and withdrawal of money from banks, processing of business data, forecasting of weather conditions, diagnosis of diseases, searching for information on the internet, etc. Computers are used extensively in schools, universities, organizations, music industry, movie industry, scientific research, law firms, fashion industry, etc. ### 1.1 Introduction The term "computer" is derived from the word "compute". Compute means to calculate. A computer is an electronic machine that accepts data from the user, processes the data by performing calculations and operations on it, and generates the desired output results. Computers perform both simple and complex operations, with speed and accuracy. This chapter discusses the history and evolution of the computer, the concept of input-process-output, and the characteristics of computers. The chapter also discusses the classification of digital computers based on their size and type, and the application of computers in different domain areas. ### 1.2 Digital and Analog Computers A digital computer uses distinct values to represent the data internally. All information are represented using the digits 0s and 1s. The computers that we use at our homes and offices are digital computers. Analog computers are another kind of a computer that represents data as variable across a continuous range of values. The earliest computers were analog computers. Analog computers are used for measuring of parameters that vary continuously in real time, such as temperature, pressure and voltage. Analog computers may be more flexible but generally less precise than digital computers. A slide rule is an example of an analog computer. This book deals only with the digital computer and uses the term "computer" for them. ### 1.3 Characteristics of Computer Speed, accuracy, diligence, storage capability and versatility are some of the key characteristics of a computer. A brief overview of these characteristics are: * **Speed:** The computer can process data very fast, at the rate of millions of instructions per second. Some calculations that would have taken hours and days to complete otherwise, can be completed in a few seconds using the computer. For example, calculation and generation of salary slips of thousands of employees of an organization, weather forecasting that requires analysis of a large amount of data related to temperature, pressure and humidity of various places, etc. * **Accuracy:** Computers provide a high degree of accuracy. For example, the computer can accurately give the result of division of any two numbers up to 10 decimal places. * **Diligence:** When used for a longer period of time, the computer does not get tired or fatigued. It can perform long and complex calculations with the same speed and accuracy from the start till the end. * **Storage Capability:** Large volumes of data and information can be stored in the computer and also retrieved whenever required. A limited amount of data can be stored, temporarily, in the primary memory. Secondary storage devices like floppy disk and compact disk can store a large amount of data permanently. * **Versatility:** The computer is versatile in nature. It can perform different types of tasks with the same ease. At one moment you can use the computer to prepare a letter document and in the next moment you may play music or print a document. * **Limitations:** Computers have several limitations too. A computer can only perform tasks that it has been programmed to do. Computers cannot do any work without instructions from the user. It executes instructions as specified by the user and does not take its own decisions. ### 1.4 History of Computer Until the development of the first generation computers based on vacuum tubes, there had been several developments in the computing technology related to the mechanical computing devices. The key developments that took place till the first computer was developed are as follows: * **Calculating Machines**: * **Abacus** was the first mechanical calculating device for counting of large numbers. The word "abacus" means "calculating board". It consists of bars in horizontal positions on which sets of beads are inserted. The horizontal bars have 10 beads each, representing units, tens, hundreds, etc. * **Napier's Bones** was a mechanical device built for the purpose of multiplication in 1617 AD. by an English mathematician John Napier. * **Slide Rule** was developed by an English mathematician Edmund Gunter in the 16th century. Using the slide rule, one could perform operations like addition, subtraction, multiplication and division. It was used extensively till late 1970s. * **Pascal's Adding and Subtraction Machine** was developed by Blaise Pascal. It could add and subtract. The machine consisted of wheels, gears and cylinders. * **Leibniz's Multiplication and Dividing Machine** was a mechanical device that could both multiply and divide. The German philosopher and mathematician Gottfried Leibniz built it around 1673 * **Punch Card System** was developed by Jacquard to control the power loom in 1801. He invented the punched card reader that could recognize the presence of hole in the punched card as binary one and the absence of the hole as binary zero. The 0s and 1s are the basis of the modern digital computer. ### 1.6 Classification of Computer The digital computers that are available nowadays vary in their sizes and types. The computers are broadly classified into four categories based on their size and type: * **Microcomputers:** Microcomputers are small, low-cost and single-user digital computer. They consist of CPU, input unit, output unit, storage unit and the software. Although microcomputers are stand-alone machines, they can be connected together to create a network of computers that can serve more than one user. * **Minicomputers:** Minicomputers are digital computers, generally used in multi-user systems. They have high processing speed and high storage capacity than the microcomputers. Minicomputers can support 4-200 users simultaneously. The users can access the minicomputer through their PCs or terminal. They are used for real-time applications in industries, research centers, etc. * **Mainframe Computers:** Mainframe computers are multi-user, multi-programming and high performance computers. They operate at a very high speed, have very large storage capacity and can handle the workload of many users. Mainframe computers are large and powerful systems generally used in centralized databases. The user accesses the mainframe computer via a terminal that may be a dumb terminal, an intelligent terminal or a PC. * **Supercomputers:** Supercomputers are the fastest and the most expensive machines. They have high processing speed compared to other computers. The speed of a supercomputer is generally measured in FLOPS (Floating point Operations Per Second). Some of the faster supercomputers can perform trillions of calculations per second. Supercomputers are built by interconnecting thousands of processors that can work in parallel. ### 1.7 The Input-Process-Output Concept A computer is an electronic device that: 1. Accepts data 2. Processes data 3. Generates output 4. Stores Data The concept of generating output information from the input data is also referred to as input-process-output concept. ### Questions: 1. Define an analog computer and a digital computer. 2. Give an example each of analog computer and digital computer. 3. List the main characteristics of the computer. 4. Describe the characteristics of the computer. 5. List three significant limitations of the computer. 6. Explain briefly the developments in computer technology starting from simple calculating machine to the first computer. 7. What is a calculating machine? 8. What is the key feature of the Jacquard's punch card? 9. Name the first calculating device for the counting of large numbers. 10. Who is called the Father of Computer? 11. The first generation computers used ______ for circuitry. 12. Describe the first generation computer based on the *(a) Hardware (b) Software (c) Computing characteristics (d) Physical appearance and (e) Their applications.* 13. Give two examples of first generation computers. 14. List the drawbacks of the first generation computers. 15. The second generation computers used ______ for circuitry. 16. Describe the second generation computer based on the *(a) Hardware (b) Software (c) Computing characteristics (d) Physical appearance and (e) Their applications.* 17. Give two examples of second generation computers. 18. List the drawbacks of the second generation computers. 19. The third generation computers used ______ for circuitry. 20. Describe the third generation computer based on the *(a) Hardware (b) Software (c) Computing characteristics (d) Physical appearance, and (e) Their applications.* 21. Give two examples of third generation computers. 22. List the drawbacks of the third generation computers. 23. The fourth generation computers used ______ for circuitry. 24. Describe the fourth generation computer based on the *(a) Hardware (b) Software (c) Computing characteristics (d) Physical appearance and (e) Their applications.* 25. Give two examples of fourth generation computers. 26. List the drawbacks of the fourth generation computers. 27. The fifth generation computers used ______ for circuitry. 28. Describe the fifth generation computer based on the *(a) Hardware (b) Software (c) Computing characteristics (d) Physical appearance and (e) Their applications.* 29. Give two examples of fifth generation computers. 30. Compare in detail the five generations of computers based on the *(a) Hardware (b) Software (c) Computing characteristics (d) Physical appearance and (e) Their applications.* Also give at least one example of each generation of computer. 31. Define microcomputer. 32. Give two examples of microcomputer. 33. List three categories of microcomputers. 34. Define minicomputers. 35. Give two examples of minicomputer. 36. Define mainframe computer. 37. Give two examples of mainframe computer. 38. Define a dumb terminal. 39. Define an intelligent terminal.