COMPUTERS

[Music] a modern adding machine this hundred-year-old counting engine and this machine from a modern office are all counting tools we call these machines computers how do computers work and how do they help us in our everyday lives three [Music] since the beginning of history man has shown his need to count things at first he probably counted on his fingers but man soon found that other counting tools could help him count more rapidly and accurately one of the earliest counting machines was the abacus some of these kinds of computers are still in use in many parts of the world but as world population grew and life became more complex the need for more efficient tools increased 300 years ago man turned to mechanical devices to help him count these new mechanical computers depended upon gears levers and weights to perform the counting operations they were slow noisy and only slightly more dependable than man himself more than 100 years ago charles babbage designed a computer that could add subtract multiply divide and store information but because the machinists of his day were not skilled enough to produce the parts he needed this machine was never really completed nevertheless babbage's machine was the forerunner of our modern digital computers today's computers use electronic circuits in place of the old mechanical systems inside this little plastic box is a miniature electronic circuit electronic circuits are far more reliable than gears and levers have no moving parts work at very high speeds and can store great quantities of information needed to keep the records of our rapidly changing society all computers have five basic parts an input unit that receives information a storage or memory unit an arithmetic unit that does the computing an output unit that delivers information and a control unit computers need two kinds of input instructions to perform certain operations in a certain order and information needed to carry out the instructions the input information can enter the computer in several ways it can be on punched cards [Applause] or the input can be on magnetic tapes or magnetic discs information can also be given directly to the computer by typewriter or by drawing diagrams with a special pen the computer converts information from all of these inputs into a form with which it can work electrical pulses bits of information pass from the input unit in the form of electrical pulses to the storage unit there each bit of information has its place on a memory core these cores are smaller than pin heads and the storage unit of a large computer may have millions of them in the arithmetic unit computations are carried out computers can perform all the counting operations addition subtraction multiplication division and comparison of numbers these lights tell us that computations are being done in the arithmetic unit information is brought from the storage unit arithmetic operations performed and the results are then returned to storage computers can deliver information or output in several ways this high-speed printer changes the computer's calculations and electrical pulses back into a form which we can read or the output may be printed by a computer-operated typewriter or appear on a screen like a television screen the control unit directs the operation of the other four units so that every step is performed at the right time [Music] we usually count with a system based on ten but because computers are electronic they use a system based on the two electrical conditions on and off we call this a binary number system we can demonstrate this system by switching lights on and off here the lights are counting from one to fifteen with enough lights any number could be shown computers work so fast they can handle inputs from many different people at the same time this is called time sharing as far as these operators are concerned each one has the computer to himself but actually the computer rotates its attention among them giving each a small fraction of every second time sharing makes computers useful for many more people than would otherwise be possible computers may be part of a school program these high school students are learning to use their classroom computer god [Applause] every day new uses are found for computers large-scale industrial processes such as chemical manufacturing use computers to control production air traffic controllers depend on computers to accurately schedule flights and it is computers that have made our entire space program possible um [Applause] [Music] [Applause] back on earth computers help repair the bills that come to your home they help keep records of charge accounts memberships in organizations and bank accounts computers are becoming more and more widely used if you look around you'll see many ways that computers are affecting your daily life [Music]