History-of-comp.pdf

History of Computers  Computer  was originally a job title: it was used to describe those human beings (predominantly women) whose job it was to perform the repetitive calculations required to compute such things as navigational tables, tide charts, and planetary positions for ast...

History of Computers  Computer  was originally a job title: it was used to describe those human beings (predominantly women) whose job it was to perform the repetitive calculations required to compute such things as navigational tables, tide charts, and planetary positions for astronomical almanacs. The Abacus  was an early aid for mathematical computations.  Its only value is that it aids the memory of the human performing the calculation. A skilled abacus operator can work on addition and subtraction problems at the speed of a person equipped with a hand calculator (multiplication and division are slower).  The abacus is often wrongly attributed to China. In fact, the oldest surviving abacus was used in 300 B.C. by the Babylonians. A very old Abacus Napier's Bones In 1617 Scotsman named John Napier invented logarithms, which are a technology that allows multiplication to be performed via addition. The magic ingredient is the logarithm of each operand, which was originally obtained from a printed table. invented an alternative to tables, where the logarithm values were carved on ivory sticks. slide rule  first built in England in 1632 and still in use in the 1960's by the NASA engineers of the Mercury, Gemini, and Apollo programs which landed men on the moon. Adding Machine 1642 Blaise Pascal, at age 19, invented the Pascaline as an aid for his father who was a tax collector. Pascal built 50 of this gear-driven one-function calculator (it could only add) but couldn't sell many because of their exorbitant cost and because they really weren't that accurate  Calculating Machine (stepped reckoner) German Gottfried Wilhelm Leibnitz (build a four-function (addition, subtraction, multiplication, and division) calculator that he called the stepped reckoner instead of gears, it employed fluted drums having ten flutes arranged around their circumference in a stair-step fashion.  (each drum had 10 flutes), Leibnitz was the first to advocate use of the binary number system which is fundamental to the operation of modern computers. Leibnitz is considered one of the greatest of the philosophers but he died poor and alone. Punched Cards  In1801 the Frenchman Joseph Marie Jacquard invented a power loom that could base its weave (and hence the design on the fabric) upon a pattern automatically read from punched wooden cards, held together in a long row by rope.  1822 the English mathematician Charles Babbage was proposing a steam driven calculating machine the size of a room, which he called the Difference Engine. This machine would be able to compute tables of numbers, such as logarithm tables. Analytic Engine  This device, large as a house and powered by 6 steam engines, would be more general purpose in nature because it would be programmable  two main parts of his Analytic Engine the "Store" and the "Mill“, Store was where numbers were held and the Mill was where they were "woven" into new results.  A central shaft driven by an outside waterwheel and connected to each machine by overhead belts was the customary power source for all the machines in a factory Hollerith desk Herman Hollerith, adopted Jacquard's punched cards for the purpose of computation. consisted of a card reader which sensed the holes in the cards, a gear driven mechanism which could count (using Pascal's mechanism which we still see in car odometers), and a large wall of dial indicators (a car speedometer is a dial indicator) to display the results of the count. Hollerith built a company, the Tabulating Machine Company which, after a few buyouts, eventually became International Business Machines, known today as IBM. IBM grew rapidly and punched cards became ubiquitous. Mark I  builtas a partnership between Harvard and IBM in 1944. This was the first programmable digital computer made in the U.S. not a purely electronic computer. It was constructed out of switches, relays, rotating shafts, and clutches. The machine weighed 5 tons, incorporated 500 miles of wire, was 8 feet tall and 51 feet long, and had a 50 ft rotating shaft running its length, turned by a 5 horsepower electric motor. The Mark I ran non-stop for 15 years, sounding like a roomful of ladies knitting. ENIAC I 1946, John Mauchly and John Presper Eckert developed the ENIAC I (Electrical Numerical Integrator And Calculator). The American military sponsored their research; the army needed a computer for calculating artillery-firing tables, the settings used for different weapons under varied conditions for target accuracy.  17,468 vacuum tubes, along with 70,000 resistors, 10,000 capacitors, 1,500 relays, 6,000 manual switches and 5 million soldered joints. It covered 1800 square feet (167 square meters) of floor space, weighed 30 tons, consumed 160 kilowatts of electrical power. There was even a rumor that when turned on the ENIAC caused the city of Philadelphia to experience brownouts,  In one second, the ENIAC (one thousand times faster than any other calculating machine to date) could perform 5,000 additions, 357 multiplications or 38 divisions  1 gen.-1946-1958 st Vacuum Tubes UNIVAC (UNIVersal Automatic Computer),  The first generation computers were huge, slow, expensive, and often undependable. In 1946 two Americans, Presper Eckert, and John Mauchly built the ENIAC electronic computer which used vacuum tubes instead of the mechanical switches of the Mark I. The ENIAC used thousands of vacuum tubes, which took up a lot of space and gave off a great deal of heat just like light bulbs do. The ENIAC led to other vacuum tube type computers like theEDVAC (Electronic Discrete Variable Automatic Computer) and the UNIVAC I (UNIVersal Automatic Computer).  Mainframe  2nd Gen. 1959-1964 The Era of Transistors  Transistor which functions like a vacuum tube in that it can be used to relay and switch electronic signals.  The transistor was faster, more reliable, smaller, and much cheaper to build than a vacuum tube. One transistor replaced the equivalent of 40 vacuum tubes. These transistors were made of solid material, some of which is silicon, an abundant element (second only to oxygen) found in beach sand and glass. Therefore they were very cheap to produce. Transistors were found to conduct electricity faster and better than vacuum tubes.  3 Gen. 1965-1970 rd IC- Integrated Circuit  referred to as semiconductor chip, packs a huge number of transistors onto a single wafer of silicon.  4th Gen. 1971-Today Microprocessor - Brains of the computer – Most computers have several processors – Central Processing Unit (CPU)  Types of computers (classification based on operational principle)  Analog Computers  isalmost an extinct type of computer. It can perform numerous mathematical operations simultaneously. It is also unique in terms of operation as it utilizes continuous variables for the purpose of mathematical computation. It utilizes mechanical, hydraulic, or electrical energy or operation.  Hybrid computers a combination of both Analog and Digital computers.  hybrid types of computers the Digital counterparts convert the analog signals to perform Robotics and Process control. Computers are also categorized on the basis of physical structures and the purpose of their use. Based on Capacity, speed and reliability they can be divided into three categories of computers: The Mainframe Computer The Microcomputer The Mini computer  The Mainframe Computer  These are computers used by large organizations like meteorological surveys and statistical institutes for performing bulk mathematical computations. They are core computers which are used for desktop functions of over one hundred people simultaneously.  The Microcomputer These are the most frequently used computers better known by the name of Personal computers. This is the type of computer meant for public use. Other than Desktop Computer the choice ranges as follows:  Tablet PC  Towers  Work Stations  Laptops  Hand Held Computer  Smart phones  The Minicomputer  Mini computers like the mainframe computers are used by business organization. The difference being that it can support the simultaneous working of up to 100 users and is usually maintained in business organizations for the maintenance of accounts and finances.  Super Computers  It is somewhat similar to mainframe computers and is used in economic forecasts and engineering designs  The most powerful computers made  Handle large and complex calculations  Process trillions of operations per second  Found in research organizations  The five elements of a computer system  input devices examples: Keyboard, mouse  output devices examples: Monitor, printer, speaker  control unit - It directs the flow of data between the Central Processing Unit (CPU) and the other devices.  arithmetic and logical unit (ALU)  storage (internal and external)  Random Access Memory (RAM) Volatile Stores current data and programs  Read Only Memory (ROM) Permanent storage of programs  Components of a Computer System  hardware - components of a computer system are the electronic and mechanical parts. output devices  software components of a computer system are the intangible parts: the data and the computer programs. storage  Peopleware/user  Data