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Structure
1.1 Introduction to Computer 1.2 Classification of Computers 1.3 Anatomy of Computers 1.4 Number Systems 1.5 Input Output devices 1.6 Memory Unit 1.7 Language / Software 1.8 Utilities
Learning Objectives
· Define a computer · Identify the characteristics of a computer · Appreciate the evolution of computer through five generations · Classification of computers · Functionality of various parts of computer through the Block diagram · Types of number systems
UNIT 1
Introduction to Computers and
Generations of Computers
2 Computer Graphics and Animation · Binary, octal, decimal and Hexa-decimal number systems · Conversions from one system to another system · Explain the concept input, output · Explain various input devices · Explain various output devices · What is main memory · What is memory size · What is secondary memory · What are RAM, ROM, PROM, EAPROM, Cache memory and registers · Secondary storage devices such as magnetic tape, disk, cd’s, flash drive Etc., · Explain the concept of software · Distinguish between different types of software · Differentiate application software from system software · Define a language · Differentiate between different types of language · Distinguish between compiler and interpreter
1.1 Introduction
The term Computer is derived from ‘compute’ which means ‘to calculate’. We are all familiar with calculations in our day-to-day life. We apply mathematical operations like addition, subtraction, multiplication, etc. and many other formulae for calculations. Simple calculations take less time. But complex calculations take much longer time. Another factor is accuracy in calculations. So man explored with the idea to develop a machine, which can perform this type of arithmetic calculation faster, and with full accuracy. This gave birth to a machine called ‘computer’. What is a Computer You have already experienced the impact of computers in our day to-day life. Reservation of tickets in Air Lines and Railways, Payment of telephone and
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6. Automation Once the instructions fed into computer it works automatically without any human intervention until the completion of execution of program or meets logical instructions to terminate the job. 7. Diligent A computer is free from tiredness, lack of concentration, fatigue, etc. It can work for hours without creating any error. If millions of calculations are to be performed, a computer will perform every calculation with the same accuracy. Due to this capability it overpowers human being in routine type of work. 1.1.3 The Computer Generations : The evolution of computer started from 16th century and resulted in the form that we see today. The present day computer, however, has also undergone rapid change during the last fifty years. This period, during which the evolution of computer took place, can be divided into five distinct phases, basis of the type of switching circuits known as Generations of Computers. 1. First Generation Computers (1950’s) These computers which used vacuum tubes (valves) as major electronic component. The advantage of vacuum tubes technology is that it made the advent of Electronic digital computer. Vacuum tubes were only electronic devices available during those days which made computing possible. 2. Second Generation Computers (1960’s) Around 1955 a device called Transistor replaced the bulky electric tubes in the first generation computer. Transistors are smaller than electric tubes and have higher operating speed. They have no filament and require no heating. Manufacturing cost was also very low. Thus the size of the computer got reduced considerably. 3.Third Generation Computers (1970’s) The third generation computers were introduced in 1964. They used Integrated Circuits (ICs). These ICs are popularly known as Chips. A single IC has many transistors, registers and capacitors built on a single thin slice of silicon. So it is quite obvious that the size of the computer got further reduced. Computers of this generation were small in size, low cost, large memory and processing speed is very high.
Paper - I Computer Fundamentals and MS-Office 5
4. Fourth Generation (1980’s) The present day computers that you see today are the fourth generation computers that started around 1975. It uses large scale Integrated Circuits (LSIC) built on a single silicon chip called microprocessors. Due to the development of microprocessor it is possible to place computer’s central processing unit (CPU) on single chip. These computers are called microcomputers. Later very large scale Integrated Circuits (VLSIC) replaced LSICs. Thus the computer which was occupying a very large room in earlier days can now be placed on a table. The personal computer (PC) that you see in your college is a Fourth Generation Computer. 5. Fifth Generation (Late 1990’s) These computers use optic fiber technology to handle Artificial Intelligence, expert systems, Robotics etc., these computers have high processing speeds and are more reliable.
1.2 Classification of Computers
The computers are classified into various types depends on their purpose, operation and size. Classification of Computers In general computers are classified into major categories based on. (a) According to the purpose of the computer. (b) According to the operation of computer. (c) According to the size of computer. (a) Classification as per purpose of the computer
- General purpose computers.
- Special purpose computer. 1. General Purpose Computers : These computers are theoretically used for any type of applications. These computers can be used in solving a business Problem and also used to solve mathematical equation with same accuracy and consistency. Most of the computer now are general purpose digital computers. All the P.C’s, which have become household affair. 2. Special Purpose Computers : These digital computer are designed, made and used for any specific job. These are usually used for those purposes
Paper - I Computer Fundamentals and MS-Office 7 Mainframe Computers: Large organizations use mainframes for highly critical applications such as bulk data processing and ERP. Most of the mainframe computers have capacities to host multiple operating systems and operate as a number of virtual machines. They can substitute for several small servers. Wearable Computers: A record-setting step in the evolution of computers was the creation of wearable computers. These computers can be worn on the body and are often used in the study of behavior modeling and human health. Military and health professionals have incorporated wearable computers into their daily routine, as a part of such studies. When the users’ hands and sensory organs are engaged in other activities, wearable computers are of great help in tracking human actions. Wearable computers do not have to be turned on and off and remain in operation without user intervention Minicomputers: In terms of size and processing capacity, minicomputers lie in between mainframes and microcomputers. Minicomputers are also called mid-range systems or workstations. The term began to be popularly used in the 1960s to refer to relatively smaller third generation computers. They took up the space that would be needed for a refrigerator or two and used transistor and core memory technologies. The 12-bit PDP-8 minicomputer of the Digital Equipment Corporation was the first successful minicomputer. Microcomputers: A computer with a microprocessor and its central processing unit is known as a microcomputer. They do not occupy space as much as mainframes do. When supplemented with a keyboard and a mouse, microcomputers can be called personal computers. A monitor, a keyboard and other similar input-output devices, computer memory in the form of RAM and a power supply unit come packaged in a microcomputer. These computers can fit on desks or tables and prove to be the best choice for single-user tasks. Desktops: A desktop is intended to be used on a single location. The spare parts of a desktop computer are readily available at relatively lower costs. Power consumption is not as critical as that in laptops. Desktops are widely popular for daily use in the workplace and households. Laptops: Similar in operation to desktops, laptop computers are miniaturized and optimized for mobile use. Laptops run on a single battery or an external adapter that charges the computer batteries. They are enabled with an inbuilt keyboard, touch pad acting as a mouse and a liquid crystal display. Their portability and capacity to operate on battery power have proven to be of great help to mobile users.
8 Computer Graphics and Animation Notebooks : They fall in the category of laptops, but are inexpensive and relatively smaller in size. They had a smaller feature set and lesser capacities in comparison to regular laptops, at the time they came into the market. But with passing time, notebooks too began featuring almost everything that notebooks had. By the end of 2008, notebooks had begun to overtake notebooks in terms of market share and sales. Personal Digital Assistants (PDAs): It is a handheld computer and popularly known as a palmtop. It has a touch screen and a memory card for storage of data. PDAs can also be used as portable audio players, web browsers and smart phones. Most of them can access the Internet by means of Bluetooth or Wi-Fi communication. Tablet Computers : Tablets are mobile computers that are very handy to use. They use the touch screen technology. Tablets come with an onscreen keyboard or use a stylus or a digital pen. Apple’s iPad redefined the class of tablet computers.
1.3 Anatomy of Computers
The Computer mainly consists the functions input, process, output and storage. These functions were described in the manner of diagram as follows. The Block diagram of computer consists mainly i.e., Fig. 1.1 Block Diagram of Computer Flow of Information Control links Central Processing Unit Secondary Storage Control Unit Main memory Arithmetic & logical unit Input unit Output unit
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6. Secondary storage: It is also known as auxiliary memory. It is closely linked with the main memory. Since main memory can’t be flooded with unwanted data at particular moment, same is stored in auxiliary memory from which desired data is fed to main memory as and when required by it. Thus secondary storage is used to hold mass of information i.e., system software, application programs, cinemas, games and data files. Obviously the capacity of secondary storage is very high compared to main memory. Auxiliary memory usually in the form of Magnetic disk, Magnetic tape, CD’s, Memory cards, Pen drives Etc.,
1.4 Number Systems
The data representation of computer consists alphabets, numerals, and special symbols. Here we discuss about the numerals(numbers). In our daily life we use decimal system ,where as computer use only binary system .But there are four types of number systems. The number system Basically Number system is divided in to four types
- Binary Number System
- Octal Number system
- Decimal Number system
- Hexa-decimal Number System 1. Binary Number System :-It is base(radix) of 2 and it has only two digits i.e 0 and 1. The value of the numbers is represented as power of 2 i.e. the radix of the system. These power increases with the position of the digits as follows 2.Octal Number System :- It is base of 8 and it has only eight digits i.e 0 ,1,2,3,4,5,6 and 7. The value of the numbers is represented as power of 8 i.e. the radix of the system. These power increases with the position of the digits as follows. Ex : (1011) 2 (11010) 2
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- Decimal Number system :- It is base of 10 and it has only ten digits i.e 0 ,1,2,3,4,5,6,7,8 and 9. The value of the numbers is represented as power of 10 i.e. the radix of the system. These power increases with the position of the digits as follows. 4. Hexa Decimal Number System :- :- It is base of 16 and it has only sixteen digits i.e 0 ,1,2,3,4,5,6,7,8,9, A(10),B(11), C(12), D(13),E(14) and F(15). The value of the numbers is represented as power of 16 i.e. the radix of the system. These power increases with the position of the digits as follows Conversions We can convert from any system to any other system as follows. 1. Decimal to Binary Divide the decimal number by 2 repeatedly and note the remainders from bottom to top. Ex : (259) 10 (184) 10 Ex : (5D) 16 (1A5) 16
Paper - I Computer Fundamentals and MS-Office 13 Ex2: convert (124) 10 to (?) 8 8 124 8 15 4 1 7 3.Decimal to hexadecimal: Divide the decimal number by 16 repeatedly and note the remainders from bottom to top. Ex1: Convert (50) 10 to (?) 16 16 50 3 2 (32) 16 Ex2: Convert (380) 10 to (?) 16 16 380 16 23 C 1 7 (17C) 16
- Binary to Decimal: Multiply the binary number with the weights of binary system according to theirposition and note the sum. Ex1: Convert (11010) 2 to (?) 10 11010 = 1 x 2 4 +1 x 2^3 + 0 x 2^2 +1 x 2^1 + 0 x 2^0 = 1 x 16 + 1 x 8 + 0 x 4 + 1 x 2 + 0 x 1
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5.Octal to Decimal: Multiply the Octal number with the weights of octal
6. Hexadecimal to Decimal: Multiply the hexadecimal number with the
- = 16 + 8 + 0 +2 + 0 = (26)
- Ex2: Convert (1101) 2 into (?)
- 1101 = 1 x 2^3 + 1 x 2^2 +0 x 2^1 + 1 x - = 1 x 8 + 1 x 4 + 0 x 2 + 1 x - = 8 + 4 + 0 +1 = (13)
- Ex1: Convert (62) 8 into (?) system according to their position and note the sum. - (62) 8 = 6 x 8^1 + 2 x - = 6 x 8 + 2 x - = 48 + 2 = (50)
- Ex2: Convert (174) 8 into (?) - (174) 8 = 1 x 8^2 + 7 x 8^1 + 4 x - = 1 x 64 + 7 x 8 + 4 x - = 64 + 56 + 4 = (124)
- Ex1: Convert (5D) 16 into (?) weights of hexadecimal system according to their position and note the sum.
- (5D) 16 = 5 x 16^1 + D x - = 5 x 16 + 13 x - = 80 + 13 = (93)
- Ex2: Convert (1A5) 16 into (?)
- (1A5) 16 = 1 x 16^2 + A x 16^1 + 5 x - = 1 x 256 + 10 x 16 + 5 x - = 256 + 160 + 5 = (421)
16 Computer Graphics and Animation OMR is widely used in tests such as aptitude tests. 1.5.4.5 Bar Code Reader These devices are generally available in super markets, bookshops, etc. Bar-code readers are photoelectric scanners that read the bar codes or vertical zebra striped marks, printed on product containers. Supermarkets use a bar code system called the Universal Product Code (UPC). The bar code identifies the product to the supermarket’s computer which has a description and the latest price of the product. The computer automatically tells the Point of Sales (POS) terminal what the price is. 1.5.2.6 Digitizing Tablet This is an input device that enables you to enter drawings and sketches into a computer. A digitizing tablet consists of an electronic tablet and a cursor or pen. A cursor (also called a puck) is similar to a mouse, except that it has a window with cross hairs for pinpoint placement, and it can have as many as 16 buttons. A pen (also called a stylus) looks like a simple ballpoint pen but uses an electronic head instead of ink. The tablet contains electronic field that enables it to detect movement of the cursor or pen and translate the movements into digital signals that it sends to the computer. Digitizing tables are also called digitizers, graphics tables, touch tables or simply tables. 1.5.2.7 Scanner Scanner is an input device that can read text or illustrations printed on paper and translate the information into a form that the computer can use. A scanner works by digitizing an image - dividing it into a grid of boxes and representing each box with either a zero or a one, depending on whether the box is filled in. The resulting matrix of bits, called a bit map, can then be stored in a file, displayed on a screen and manipulated by programs. Optical scanners do not distinguish text from illustrations, they represent all images as bit maps. Therefore, you cannot directly edit text that has been scanned. To edit text read by an optical scanner, you need an optical character recognition (OCR) system to translate the image into ASCII characters. Most optical scanners sold today come with OCR packages. 1.5.2.8 Mouse Mouse is a device that controls the movement of the cursor or pointer on a display screen. It is a small object you can roll along a hard and flat surface. As you move the mouse, the pointer on the display screen moves in the same direction.
Paper - I Computer Fundamentals and MS-Office 17 Mouse contains at least one button and sometimes as many as three, which have different functions depending on what program is running. 1.5.2.9 Light Pen Light pen is an input device that utilizes a light-sensitive detector to selectobjects on a display screen. 1.5.2.10 Speech input devices Speech or voice input devices convert a person’s speech into digital form. These input devices, when combined with appropriate software, form voice recognition systems. These systems enable users to operate microcomputers using voice commands. 1.5.3 Output Devices Output devices receive information from the CPU and present it to the user in the desired form. Output devices include display screen, loudspeakers, printers, plotters, etc. 1.5.3.1 Display Screen When a program is keyed in, the screen (which is similar to a television screen) displays the characters. The user can read the program line by line and make corrections before it is stored or printed on a printer. It is also possible to bring to the screen a portion of the program stored in the external storage for editing. Screen sizes differ from system to system. The standard size is 24 lines by 80 characters. Most systems have provision for scrolling. This facilitates the user to move the text vertically or horizontally on the screens thus bringing to the screen the hidden text. Thus the user can scan through the entire file either to review or to select a particular portion. The cursor on the screen is controlled by the cursor keys on the keyboard, 1.5.3.2 Printer Printer is a device that prints text or illustrations on paper and in many cases on transparencies and other media. There are many different types of printers. In terms of the technology utilized, printer fall into the following categories. (i) Ink-jet Printer Ink-jet printers work by spraying ionized ink on a sheet of paper. Magnetized plates in the ink’s path direct the ink onto the paper in the desired shapes. Inkjet printers are capable of producing high quality print approaching to that produced
Paper - I Computer Fundamentals and MS-Office 19 printing usually prints at 1,200 or 2,400 dpi. Some laser printers achieve higher resolutions with special techniques known generally as resolution enhancement. In addition to text, laser printers are very adept at printing graphics. However, you need significant amounts of memory in the printer to print high- resolution graphics. To print a full-page graphic at 300 dpi, for example, you need at least 1 MB (megabyte) of printer RAM. For a 600-dpi graphic, you need at least 4 MB RAM. The speed of laser printers ranges from about 4 to 20 pages of text per minute (ppm). A typical rate of 6 ppm is equivalent to about 40 characters per second (cps). (iii) Line Printer Line printers are high-speed printers capable of printing an entire line at one time. A fast line printer can print as many as 3,000 lines per minute. The disadvantages of line printers are that they can print only one font, they cannot print graphics, the print quality is low, and they are very noisy. (iv) Thermal printer Thermal printers are printers that produce images by pushing electrically heated pins against special heat-sensitive paper. Thermal printers are inexpensive and are used in most calculators and many fax machines. They produce low- quality print, and the paper tends to curl and fade after a few weeks or months. 1.5.3.3 Plotter Plotter is a device that draws pictures on paper based on commands from a computer. Plotters differ from printers in that they draw lines using a pen. As a result, they can produce continuous lines, whereas printers can only simulate lines by printing a closely spaced series of dots. Multicolour plotters use different- coloured pens to draw different colours. Fig. 1.2 Plotter
20 Computer Graphics and Animation In general, plotters are considerably more expensive than printers. They are used in engineering applications where precision is mandatory. 1.5.3.4 Sound Cards & Speakers An expansion board that enables a computer to manipulate and output sounds. Sound cards are necessary for nearly all CD-ROMs and have become commonplace on modern personal computers. Sound cards enable the computer to output sound through speakers connected to the board, to record sound input from a microphone connected to the computer, and manipulate sound stored on a disk. Nearly all sound cards support MIDI, a standard for representing music electronically. In addition, most sound cards are Sound Blaster-compatible, which means that they can process commands written for a Sound Blaster card, the de facto standard for PC sound. Fig. 1.3 Sound Card and Speakers 1.5.3.5 3D-Audio 3D audio is a technique for giving more depth to traditional stereo sound. Typically, 3D sound, or 3D audio, is produced by placing a device in a room with stereo speakers. The device dynamically analyses the sound coming from the speakers and sends feedback to the sound system so that it can readjust the sound to give the impression that the speakers are further apart. 3D audio devices are particularly popular for improving computer audio where the speakers tend to be small and close together. There are a number of 3D audio devices that can be attached to a computer’s sound card.
