Computer introduction

Slide 1: 

4/23/2011 REKHA GOYAL Input Secondary Storage Primary Storage Control Unit ALU Output Central Processing Unit Block Diagram Of Computer System Data Results

Input Unit : 

4/23/2011 REKHA GOYAL Input Unit Data and Instructions must enter a computer system before any computation on the data. The input unit that links a compute with its external environment perform this task. Input Interface transform input into binary codes. Input Interface performs following functions: It accepts instruction and data from outside It converts the data and instructions in binary form It supplies converted instructions to computer system.

Output Unit : 

4/23/2011 REKHA GOYAL Output Unit An output unit supplies information to user. A computer work with binary codes, results produced are also in binary form. Therefore before supplying the results to user the output interface must convert them to high language. It accepts the results produced by a computer It converts these coded results into readable form It supplies the converted results to the user

Storage Unit : 

4/23/2011 REKHA GOYAL Storage Unit Data and instructions have to be saved into the computer before actual processing starts. Storage unit provides the space for storing 1. Data and Instructions required for processing 2. Intermediate results of processing 3. Results for output

Arithmetic and Logical Unit : 

4/23/2011 REKHA GOYAL Arithmetic and Logical Unit Arithmetic Logic unit is the place where actual processing of instructions takes place. Calculations and Comparisons are done in the ALU. Data & Instructions stored in primary memory before processing are transferred to the ALU. Arithmetic Operations are: +,-,*,%,/ Comparisons Operations are:<,>,=,<=,>=

Control Unit : 

4/23/2011 REKHA GOYAL Control Unit 1. How does an input device know that it is time for storing data into storage unit? 2. How does the ALU know what should be done with the data? 3. How it is that only results for output are sent to an output device not the intermediate results? All this is possible due to the control unit of the computer system. It manages and coordinates the entire computer system. It takes instructions, interprets the instructions and issues the signals for other units of the system to execute them.

Central Processing Unit : 

4/23/2011 REKHA GOYAL Central Processing Unit Control Unit and Arithmetic Logic Unit of a computer are together known as the Central Processing Unit. The CPU is the brain of the computer. CPU is responsible for activating and controlling the operations of the other units of the computer system.

Classification Of Computers : 

4/23/2011 REKHA GOYAL Classification Of Computers General Purpose Computers come in many sizes and capabilities. Traditionally Computers were classified by their size, processing speed and cost. Based on these factors, computers were classified as Microcomputers, Minicomputers, Mainframes and Supercomputers. However with changing technology new models of computers are introduced having much higher performance and costing less than their preceding models. Today computers are classified based on their mode of use i.e. Notebook, Personal computer, Workstations, Mainframes and Client & Server computers and Handled Computers.

Notebook Computers (Laptop) : 

4/23/2011 REKHA GOYAL Notebook Computers (Laptop) Notebook computers are portable computers mainly meant for use by people who need computing wherever they go. The size of a notebook computer is 8 and1/2 by 11 inches and can easily fit in a briefcase. Notebook computers are light in weight. A notebook computer uses a keyboard, a flat screen and a trackball and touchpad. It also has a hard disc, floppy disc drive, CD or DVD drive and ports for connecting peripheral devices such as printer, pen drive, etc.

PERSONAL COMPUTERS : 

4/23/2011 REKHA GOYAL PERSONAL COMPUTERS A PC is a non portable general purpose computer that fits on a table and is used by one person at a time. Users use PC for his personal computing needs. System configuration of PC varies depending on the users. The most commonly used configuration is a monitor, keyboard and mouse, hard disc storage, floppy disc drive, CD or DVD drive, any special add on cards and ports for connecting peripheral devices.

WORK STATIONS : 

4/23/2011 REKHA GOYAL WORK STATIONS A workstation is a desktop computer designed to meet the needs of engineers, architects, and other professionals who need greater processing power, larger storage and better graphic display than PC. For e.g.: Workstations are used for CAD, simulation of complex scientific and engineering problems, visualization of results of simulation and multimedia applications. Processing power of a workstation is more than that of PC. Workstations have larger main memory(GB) as compared to PC(MB). Most workstations have a large screen monitor capable of displaying high resolution graphics. Workstations use CPU’s based on RISC technology. Workstations run the UNIX operating system or Solaris operating system.

MAINFRAME COMPUTERS : 

4/23/2011 REKHA GOYAL MAINFRAME COMPUTERS Mainframe systems are used for handling data for mid or large sized organizations such as banks, hospitals, railways, insurance companies etc. that need online processing of large number of transactions and require computer system having large data storage and processing capabilities. Mainframe systems are used in such environments where large number of users need to share a common computing facility. Mainframe system is located in a central location with several user terminals.

SUPERCOMPUTERS : 

4/23/2011 REKHA GOYAL SUPERCOMPUTERS Supercomputers are expensive computers. They are used for processing complex scientific applications i.e. Petroleum industry uses supercomputers to analyze volume of seismic data gathering during oil seeking explorations to identify areas where there is possibility of getting petroleum products inside the earth. Automobile industry uses supercomputers to do crash simulation of an automobile before it is released for manufacturing.

SUPERCOMPUTERS : 

4/23/2011 REKHA GOYAL SUPERCOMPUTERS Supercomputers use multi processing and parallel processing to solve complex problems faster because they use multiple processors. A parallel program is written in a manner to break up an original problem into smaller modules that can be allocated to different processor and multiple processor can work independently to solve it. Supercomputers support multiprogramming allowing simultaneous access by multiple users.

Client & Server Computers : 

4/23/2011 REKHA GOYAL Client & Server Computers With increased popularity of computer networks, it has become possible to interconnect several computers that can communicate with each other. In such computing environment several resources can be shared among multiple users for cost effective usage and can be best managed. It is usual to have one process that owns a resource and is in charge of managing it. The process that owns the resource and does this management is called a server process. Other processes that send service request to the server are called client process.

HANDHELD COMPUTERS : 

4/23/2011 REKHA GOYAL HANDHELD COMPUTERS A handheld computer is a small computing device that can be used by holding in hand. Its size, weight and design are such that it can be used comfortably by holding in hand. It is also known as palmtop because it can be kept on the palm. Some handled computers are tablet PC, PDA/Pocket PC and Smartphone.

PDA/POCKET PC : 

4/23/2011 REKHA GOYAL PDA/POCKET PC Personal Digital Assistant was initially introduced as Personal Information Manager device. PIM include contact list, calendar task, e-mail, pocket word-processing, pocket spreadsheet application etc. PDA has the LCD screen with a pen for handwriting recognition. With add-on memory cards its storage can be increased. Some PDA also provide USB port to connect external devices. Newer PDA’s also pack network capability using WiFi, Bluetooth etc.

SMARTPHONE : 

4/23/2011 REKHA GOYAL SMARTPHONE Smart phone is a fully functional mobile phone with computing power. The difference between a PDA and Smart phone is a computing platform like PC with optional phone capability.

COMPUTER GENERATIONS : 

4/23/2011 REKHA GOYAL COMPUTER GENERATIONS Generation provides a framework for the growth of computer industry. Originally the term “Generation” was used to distinguish between varying hardware technologies but it has now been extended to include both hardware and software that together make up a computer system. The custom of referring to computer era in terms of generations came into wide use only after 1964.

FIRST GENERATION(1942-1955) : 

4/23/2011 REKHA GOYAL FIRST GENERATION(1942-1955) ENIAC, EDVAC, EDSAC, UNIVAC I and IBM 701 use thousands of vacuum tubes. A vacuum tube was a glass device which used filaments as a source of electronics and could control and amplify electronic signals. It was the high speed electronic switching device available in those days. These vacuum tube computers could perform computations in milliseconds. The memory of these computers used electromagnetic relays and all data and instructions were fed into the system from punched cards. The instructions were written in assembly languages.

FEATURES : 

4/23/2011 REKHA GOYAL FEATURES They were the fastest calculating devices of their time. They were too bulky & large in size. They used thousands of vacuum tubes that emitted large amount of heat. Vacuum Tubes used filaments they had a limited life. These computers required constant maintenance. In these computers thousands of individual components were assembled manually by hand into electronic circuits. These computers were difficult and costly. These computers were difficult to program and use, they had limited commercial use.

SECOND GENERATION(1955-1964) : 

4/23/2011 REKHA GOYAL SECOND GENERATION(1955-1964) John Bardeen and Walter Brattain invented a new electronic switching device called transistor. Transistors proved to be a better electronic switching device than vacuum tubes. The second generation computers were manufactured using transistors instead of vacuum tubes. These computers were more powerful, more reliable, less expensive, smaller and cooler to operate than the first generation computers. They used magnetic cores for main memory and magnetic disk and tape for secondary storage. Punched cards were used for preparing program and data to these computers.

Slide 23: 

4/23/2011 REKHA GOYAL High Level languages like FORTRAN, COBOL, ALGOL and SNOBOL and batch operating system introduced during 2nd generation. High level languages were easier to user to understand. Batch operating system enabled multiple jobs to be together and submitted at a time. Batch operating system causes automatic transition from one job to another as soon as the former job completes. 2nd generation computers were used in business and industry for commercial data processing applications like payroll, inventory control, marketing and production planning.

FEATURES : 

4/23/2011 REKHA GOYAL FEATURES They were more easier to handle than tubes since they were made of semiconductor material rather than glass. They were highly reliable as compared to tubes. Switching circuits made of transistors could operate faster than tubes. They consume almost one-tenth power consumed by a tube. They were much smaller than a tube. They were less expensive to produce. They were more then ten times faster than 1st generation computers. They were more reliable and less prone to hardware failures.

THIRD GENERATION (1964-1975) : 

4/23/2011 REKHA GOYAL THIRD GENERATION (1964-1975) Third generation Computers were built using integrated circuits (are circuits consisting of several electronic components like transistors, registers and capacitors on a single chip of silicon) . Earlier ones used small scale integration (SSI) technology in which the integrated circuits contained only about ten to twenty components and later ones used medium scale integration (MSI) technology in which the ICs contained hundred components on a single chip. ICs were smaller, less expensive to produce, faster in operation, dissipated less heat and consumed less power.

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4/23/2011 REKHA GOYAL 3rd generation allowed construction of larger magnetic core based memory as well as larger capacity magnetic disks and tapes. Standardization of high level programming languages, timesharing operating systems and creation of independent software industry happened during 3rd generation. FORTRAN and COBOL were the most popular high level languages in those days. ANSI standardized them in 1966 and 1968 respectively. PL/I, PASCAL and BASIC high level languages were introduced. The concept of timesharing operating system was introduced which enables multiple users to directly access and share computing resources simultaneously in a manner that each user feels that no one else is using the computer.

FEATURES : 

4/23/2011 REKHA GOYAL FEATURES 1. They were more powerful than 2nd generation. 2. They were smaller than 2nd generation 3. They consumed less power. 4. They were more reliable and less prone to hardware failure. 5. Standardization of high level programming languages. 6. Timesharing Operating System helped in improving the productivity of programmers. 7. Unbundling of software from hardware. 8. Minicomputers were developed for smaller companies.

FOURTH GENERATION (1975-1989) : 

4/23/2011 REKHA GOYAL FOURTH GENERATION (1975-1989) During fourth generation personal computers were introduced and semiconductor memories replaced magnetic core memories resulting in random access memories with very fast speed. Hard disks become cheaper, smaller and larger in capacity. In addition to magnetic tapes, floppy disks became very popular. Development of high speed computer networking enabling interconnection of multiple computers to enable them to communicate and share data. LAN & WAN became popular for connecting computers within organizations or located at larger distances. Several new operating systems were developed for PCs i.e. MS-DOS, MS-Windows and Apple’s OS.

FEATURES : 

4/23/2011 REKHA GOYAL FEATURES PCs were smaller and cheaper than mainframes . They consumed less power. They had faster and larger primary and secondary memory. They were general purpose machines. Commercial production of these systems was easier and cheaper. Use of Standard high level languages allowed programs written for one computer to be easily ported on another computer. Graphical user interface enables users to quickly learn the computer. PC based application Network of computers enabled sharing of resources. PCs of 4th generations made computers affordable even by individuals.

FIFTH GENERATION (1989-Present) : 

4/23/2011 REKHA GOYAL FIFTH GENERATION (1989-Present) VLSI technology became ULSI technology in 5th generation resulting in production of microprocessor chips having ten million electronic components. Storage technology also advanced very fast making larger and larger main memory. Optical disks also emerged. Communication technologies became faster day by day and more and more computers were networked together.

FEATURES : 

4/23/2011 REKHA GOYAL FEATURES Portable PCs are much smaller and handy than PCs. More user friendly interfaces with multimedia application. Introduction of internet With so many types of computers in all price ranges.

GENERATIONS : 

4/23/2011 REKHA GOYAL GENERATIONS

GENERATIONS : 

4/23/2011 REKHA GOYAL GENERATIONS

GENERATIONS : 

4/23/2011 REKHA GOYAL GENERATIONS

GENERATIONS : 

4/23/2011 REKHA GOYAL GENERATIONS

GENERATIONS : 

4/23/2011 REKHA GOYAL GENERATIONS