Introduction to computer
Generation and Classification Of Computers pdf Some years ago, scientists began to use computer for research, math and technology, when computer became available commercially only the largest business acquired them often just for the prestige of owing one .the users of computers were quite limited in those days , today, however, it would be hard to name areas in which computer are not being used.
More peoples are buying personal computers for home use . many people use their personal computers for playing games but home computer use goes for entertainment. People are realizing the tremendous potential of home computers for gathering information using the telephone lines are specially equipped computers subscribers can call a commercials database such as CompuServe for information about the stock market current events and supports. In addition they can do their banking by computer shop via electronics catalog or enroll in accredited college courses through electronics communications system such as relearning electronics university . other popular home uses includes word processing , filling, financial planning and educational games .
In the workplace,computers have made financial analysis bookkeeping manufacturing process and other functions faster and more efficient company executives use personal computers as aids in decision making clerks and secretaries use personal computers for preparing documents and keeping records manufacturers use computers in designing machines and products controlling robots and regulating manufacturing process
Scientists build computers models of airplanes crashes in order to determine the crashes behavior of airplanes this information helps aircraft designers plan safer seats and windows and determine which fabrics and fields decrees fire hazards during during a crash .
Ecologist uses computer for monitoring problems such as acid rain and suggesting solutions for environmental management educators uses computers in classrooms for performing chemistry
Each generation of computer I characterized by a major technological development that fundamentally changed the computers operates resulting increasingly smaller , cheaper , more powerful and efficient and reliable devices.
- First Generation (1940-1956): Vacuum Tubes the first computer used vacuum tubes for circuitry and magnetic drums for memory and were often enormous,talking up entire rooms. There were very expensive to operate and in addition to using a great deal of electricity generated a lot of heat which was often the cause of malfunction first generation computers relied on machine language to perform operations and they could only solve one problem at a time input was based on punched cards and paper tapes and output was displayed on print outs examples of first generation computers are UNIVAC, LEO and ENIAC
- Second Generation (1956-1963) Transistor: transistors replaced vacuums tubes and ushered in the second generation of computers . the transistor was invented in 1947, but did not see widespread use in computers until the late 50s the transistors was far superior to the vacuum tubes allowing computers to become smaller , faster , cheaper, more energy efficient and more reliable than the first generation predecessors. Through the transistor still generated a great deal of heat that subjected the computer to damage, it was a vast improvement over the vacuum tube . second generation computers still relied on punch cards for inputs and printout for output. second generation computers moved from cryptic machine language to symbolic or assembly language, which allow programmers to specify instructions in words . it was in this era that high level compilers was made available programming language like BASIC, FORTRAN COBOL e.t.c . came out.
- Third Generation (1963- 1971)Intergreted circuit: the development of the integrated circuit was the hallmark of the third generations of computers ,transistor were miniaturized and placed on silicons chip, called semiconductor which drastically increased the speed and efficiency of computers . instead of punched cards and printouts , users interacted with third generation computers through keyboard and monitors and interface with an operating system , which allowed the device to run many different application at one time with a central program that monitored the memory. IBM360 was introduced
- Fourth Generation (1971-1991) Microprocessors, the microprocessor brought the fourth generation of computers as thousands of integrated were built onto a single silicon chip. what in the first generation filled an entire room could now fit in the palm of the hand . The Intel 4004 chip, developed in 1991 located all the components of the computers – from the centrals processing unit and memory to input / output controls on a single chip. As these small computers became more powerful they could be linked together to form networks, which eventually led to the development of the internet. Fourth generation computers also saw the development of Graphics users interface (GUI) the mouse , and handled devices . it was in this era that microcomputers and minicomputers were made available and Computers became more Popular.
- Fifth Generation: (1991 and Beyond): Artificial, intelligence, fifth generation computing devices based on artificial intelligence are still in development, though there are some application such as voice recognition , that are being used today . the use of parallel processing and superconductors is helping to make artificial intelligence a reality. Quantum computation and molecular and nanotechnology will radically change the of computer in years to come.
COMPUTER HARDWARE AND SOFTWARE
When talking out of computers,there are two terms which must be correctly distinguished , hardware and software .computer hardware refers to all the physical devices in the computer like the CPU the monitor andv the printer that can be physical felt . software is all of the instruction that a computer uses to do what you ask it to pieces of softwate are often called programs and an operating system is a large program that helps all the other programs run.
Modern digital computers are also conceptually similar regardless nevertheless they can be divided into several category on the basics of cost and performances the personal computer or microcomputer a relatively low-cost machine , usually of desktop size (though “laptops are small enough to fit in the briefcase and palm top can fit the pocket ) the workstation, a microcomputers with enhance graphics and communication capabilities that makes it especially useful for office work, the minicomputer , generally too expensive for personal use , with capacities suited to a business , school, or laboratory, and the mainframe computers , a a large , expensive machine with the capability of serving the needs of major business enterprise , governments department scientific research establishments or the like ( the largest and fastest of these are called supercomputers)….
The physical component of computer is referred to as the hardware (the hardware describes the physical aspects of computer and related devices.)
The system unit: is the actual computer ; everything else is called a peripheral device your computers system unit probably has at least one floppy disk drive and one CDs, there is another disk drive called the hard disk inside the system unit as known in figure 2.you can not remove that disk or even see it, but it is there in addition `, everything that is currently” in your computer” is actually stored on that hard disk ( we know this because there is no place else inside the computer where you can store information!)
A digital computer is not a single machine rather , it is system composed of five distinct elements;
- A central processing Unit
- Input devices
- Memory storage devices
- Output devices
- A communication network, called a bus which links all the elements of the system and connect the system to the external world.