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  1. 1st chapter Rashedul Hasan

  2. 1st Chapter. • What Computer is • -How does a Computer works • -Characteristics of Computer • -History of Computer • -Computer Generation • -Types of Computer

  3. What computer is • The word Computer derives from “Compute” means “To calculate” • Calculating device that can perform arithmetic operation at high speed. • But to define a computer merely as a calculating device is to ignore over 80% of its Function.

  4. Data processor Input process output process Data Information Store Retrieve

  5. Data & Information • Data: Data is Raw material used as input to Data processing. • Information: Information is processed data obtained as output of Data processing.

  6. Data Processing • Processing in general terms, is a series of actions or operations that converts some input into useful output. • Hence, Data processing is a series of actions or operations that converts data into output. • Data processing transforms raw data into information.

  7. Input Devices Results Of Process -ing In Human acceptable form Input data From External Source Input Data In Internal form Process -ed Data In Internal form CPU & Memory output Devices

  8. What Computer is? Four basic functions of computers include: • Receive input • Process information • Produce output • Store information

  9. Characteristics of Computer • Automatic: An automatic machine works by itself without human intervention. Computers are automatic machine as once started on a job, it carry out the job normally without human assistance until it is finished. We only need to instruct computer using coded instruction.

  10. Speed: a computer is very fast device. It can perform in a few seconds, the amount of work that a human being can do in an entire year. • Computer can perform its tasks in a microsecond (10-6), nanosecond (10-9) and even in picoseconds (10-12),

  11. Accuracy: computers are very accurate. A computer can perform every calculation with the same accuracy over again and again. • However errors can occur in computer due to incorrect input data or unreliable programs. • Garbage in garbage out [GIGO]

  12. Diligence: Computer is free from monotony, tiredness and lack of concentration. • It do not call for strike, movement for pay rise and does not create any political instability.

  13. Versatility: It is the most important characteristics of computer. One moment it is preparing results of an examination, next moment it is busy preparing salary sheet, and in between it may play your favorite songs. • This is called multitasking ability.

  14. Power of remembering: People may forget many things over the time. But in case of computer, it can recall any amount of information stored in its memory.

  15. No I.Q. : Computer has no intelligence of its own. Its I.Q. is zero, at least until today. A computer cannot take its own decision. Only a user determines what tasks a computer will perform.

  16. No feelings: Computer has no emotion. Based on our feelings, taste, knowledge and experience we often make certain judgments in our day-to-day life whereas computer can not make such judgments. • what is good & what is bad.

  17. HOW DOES A COMPUTER WORK? • The computer accepts input. Computer input is whatever is entered or fed into a computer system. Input can be supplied by a person (such as by using a keyboard) or by another computer or device (such as a diskette or CD-ROM). Some examples of input include the words and symbols in a document, numbers for a calculation, instructions for completing a process, pictures, and so on.

  18. HOW DOES A COMPUTER WORK? • • The computer performs useful operations, manipulating the data in many ways. This manipulation is called processing. Examples of processing include performing calculations, sorting lists of words or numbers, modifying documents and pictures according to user instructions, and drawing graphs. A computer processes data in the CPU.

  19. HOW DOES A COMPUTER WORK? • • The computer stores data. A computer must store data so that it is available for processing. Most computers have more than one location for storing data (the hard drive or C:\, and the floppy drive or A:\). The place where the computer stores the data depends on how the data is being used. The computer puts the data in one place while it is waiting to be processed and another place when it is not needed for immediate processing. The storage of data in the computer is called ‘online storage’ while the storage of data on computer tapes, diskettes or CD-ROMs is called ‘offline storage’.

  20. HOW DOES A COMPUTER WORK? • • The computer produces output. Computer output is information that has been produced by a computer. Some examples of computer output include reports, documents, music, graphs, and pictures. Output can be in several different formats, such as paper, diskette, or on screen.

  21. Activity Describe, in terms of input, processing and data, the production of a letter using a computer. What happens first? What happens last?

  22. You could draw a simple flow chart that showed the following: • The input for the letter is received from keyboarding, scanning or copying data from a disk • The data are processed by the computer • The data are stored in a storage device, such as a floppy disk, hard disk or magnetic tape • The computer produces output in the form of a printed letter and an electronic version that may remain in the computer for future use or reference.

  23. History of Computer • Pascal (1623-62) was the son of a tax collector and a mathematical genius. He designed the first mechanical calculator (Pascaline) based on gears. It performed addition and subtraction. • Leibnitz (1646-1716) was a German mathematician and built the first calculator to do multiplication and division. It was not reliable due to accuracy of contemporary parts.

  24. History of Computer • Babbage (1792-1872) was a British inventor who designed an ‘analytical engine’ incorporating the ideas of a memory and card input/output for data and instructions. Never actually built. • Babbage is largely remembered because of the work of Augusta Ada who was probably the first computer programmer. • Many people refer him as a father of computer. • Burroughs (1855-98) introduced the first commercially successful mechanical adding machine 1,000,000 were soldby1926.

  25. History of Computer • Hollerith developed an electromechanical punched-card tabulator to tabulate the data for 1890 U.S. census. Data was entered on punched cards and could be sorted according to the census requirements. The machine was powered by electricity. He formed the Tabulating Machine Company which became International Business Machines (IBM). IBM is currently the largest computer manufacturer, employing in excess of 300,000 people.

  26. History of Computer • Aiken (1900-73) a Harvard professor with the backing of IBM built the Harvard Mark I computer (51ft long) in 1944. It was based on relays (operate in milliseconds) as opposed to the use of gears. It required 3 seconds for a multiplication.

  27. History of Computer • Eckert and Mauchly designed and built the ENIAC in 1946 for military computations. It used vacuum tubes (valves) which were completely electronic (operated in microseconds) as opposed to the relay which was electromechanical. • It weighed 30 tons, used 18000 valves, and required 140 kwatts of power. It was 1000 times faster than the Mark I multiplying in 3 milliseconds. ENIAC was a decimal machine and could not be programmed without altering its setup manually.

  28. History of Computer • Atanasoff had built a specialised computer in 1941 and was visited by Mauchly before the construction of the ENIAC. He sued Mauchly in a case which was decided in his favour in 1974!

  29. History of Computer • Von Neumann was a scientific genius and was a consultant on the ENIAC project. He formulated plans with Mauchly and Eckert for a new computer (EDVAC) which was to store programs as well as data. • This is called the stored program concept and Von Neumann is credited with it. Almost all modern computers are based on this idea and are referred to as Von Neumann machines. • He also concluded that the binary system was more suitable for computers since switches have only two values. He went on to design his own computer at Princeton which was a general purpose machine.

  30. Examples of machines in the computer evolution: • 14th C. - Abacus - an instrument for performing calculations by sliding counters along rods or in grooves • 17th C. - Slide rule - a manual device used for calculation that consists in its simple form of a ruler and a movable middle piece which are graduated with similar logarithmic scales • 1642 - Pascaline--a mechanical calculator built by Blaise Pascal • 1804 - Jacquard loom--a loom programmed with punched cards invented by Joseph Marie Jacquard • 1850 - Difference Engine , Analytical Engine--Charles Babbage and Ada Byron Babbage's description, in 1837, of the Analytical Engine, a mechanical digital computer anticipated virtually every aspect of present-day computers.

  31. Examples of machines in the computer evolution: • 1939 -1942 - Atanasoff Berry Computer - built at Iowa State by Prof. John V. Atanasoff and graduate student Clifford Berry. Represented several "firsts" in computing, including a binary system of of arithmetic, parallel processing, regenerative memory, separation of memory and computing functions, and more. Weighed 750 lbs. and had a memory storage of 3,000 bits (0.4K). Recorded numbers by scorching marks into cards as it worked through a problem. • 1946 - ENIAC--World's first electronic, large scale, general-purpose computer, built by Mauchly and Eckert, and activated at the University of Pennsylvania in 1946. ENIAC recreated on a modern computer chip. The ENIAC is a 30-ton machine, filled with 19,000 vacuum tubes, 6000 switches, and could add 5,000 numbers in a second, a remarkable accomplishment at the time. A reprogrammable machine, the ENIAC performed initial calculations for the H-bomb. • 1940s - Colossus - Alan Turing's vacuum tube computing machines broke Hitler's Enigma codes.

  32. Examples of machines in the computer evolution: • 1950s -1960s - UNIVAC - "punch card technology" The first commercially-successful computer, introduced in 1951 by Remington Rand. Over 40 systems were sold. Its memory was made of mercury-filled acoustic delay lines that held 1,000 12-digit numbers. It used magnetic tapes that stored 1MB of data at a density of 128 cpi. UNIVAC became synonymous with computer (for a while).

  33. Evolution of Computing No Computers PCs introduced! 1960s 2001 1950 mid- 1970s Very expensive computers for large companies. Computer professionals ran the show. Powerful PCs on every desktop. Explosion of applications.

  34. Computer Generation • Generation in computer talk is step in technology. • It is used to distinguish between various hardware technologies. • Totally 4 computer generations known till today.



  37. Tubes from a 1950s computer.

  38. VACUUM TUBES • a vacuum tube is a device used to amplify, switch, otherwise modify, or create an electrical signal by controlling the movement of electrons in a low-pressure space.

  39. Characteristics of 1st Generation computer • Too big in size. • Used vacuum tube. • Power consumption of these computers was very high. • Magnetic drums were developed to store information and tapes were also developed for secondary storage. • Power consumption of these computers was very high. • Limited commercial use. Mainly used for scientific computations. • Commercial production was difficult and costly.


  41. Transistors

  42. Transistors

  43. TRANSISTORS • a transistor is a semiconductor device commonly used to amplify or switch electronic signals. • The transistor is the fundamental building block of modern electronic devices.

  44. Comparison with vacuum tubesAdvantages • Small size and minimal weight, allowing the development of miniaturized electronic devices. • Highly automated manufacturing processes, resulting in low per-unit cost. • Lower possible operating voltages, making transistors suitable for small, battery-powered applications. • No warm-up period for cathode heaters required after power application. • greater energy efficiency. • Higher reliable. • Extremely long life. Some transistorized devices produced more than 30 years ago are still in service.

  45. Characteristics of 2nd Generation computer • Faster, smaller and more reliable. • Smaller in size than first generation computer and were more reliable and less prone to hardware failure. • They were more than ten times faster than the first generation computer. • Consumed almost one-tenth the power consumed by a tube. • Were less expensive. • Commercial production was still difficult and costly. • Another major feature of the second generation was the use of high-level programming languages such as Fortran and Cobol. These revolutionised the development of software for computers.



  48. INTEGRATED CIRCUITS • an integrated circuit (also known as IC, microcircuit, microchip, silicon chip, or chip) is a miniaturized electronic circuit (consisting mainly of semiconductor devices) that has been manufactured in the surface of a thin plate of semiconductor material.

  49. Generation of I.C. • The first integrated circuits contained only a few transistors. Called "Small-Scale Integration" (SSI), they used circuits containing transistors numbering in the tens. • The next generation in the development of integrated circuits, taken in the late 1960s, introduced devices which contained hundreds of transistors on each chip, called "Medium-Scale Integration" (MSI).

  50. They were more powerful then 2nd generation computer. They were capable of performing 1 million instruction per second. • They were smaller then 2nd generation computer requiring smaller place. • They consumed less power & dissipated less heat. • Was suitable for commercial uses. • They were easier to upgrade.