A computer is a machine that is able to take information (input), do some work on or make changes to the information, to make new information (output). Computers have existed for much of human history. Examples of early computers are the astrolabe and the abacus. Modern computers are very different from early computers. They are now very powerful machines that are able to do billions of calculations every second. Most people have used a personal computer in their home or at work. Computers are useful for many different jobs where automatic tasks are useful. Some examples are controlling traffic lights, vehicle computers, security systems, Washing machines and Digital Televisions. A person (called a user) can control a computer by telling it to do things. Some ways of controlling a computer are with a keyboard, mouse, buttons, touch screen. Some very new computers can also be controlled with voice commands or hand gestures. Computers can be designed to do anything with information. Computers are used to control factories, which in the past were controlled by humans. They are also in homes, where they are used for things such as listening to music, reading the news, and writing. Modern computers are electronic machines. A computer is only useful if it has both hardware and software. Hardware is the physical parts the computer is made of - for example keyboard, mouse, screen, tower, and the circuits inside it. Software is the computer programs (mathematical instructions). The software uses the hardware, when the user gives it instructions and changing it in to useful output. Many modern computers do billions of calculations each second. They do mathematical arithmetic very quickly but computers do not really think. They only follow the instructions in their software programs. Computer programs are designed or written by computer programmers. A few programmers write programs in the computers own language called machine code. Machine Code has only a few instructions and is based on logic and Mathematical arithmetic. Using machine code is difficult for most human programmers. Today, programs are commonly written using a programming language like C++, Java, and Objective-C. These programming languages are more like the language you talk and write with every day. A program called a compiler translates the users instructions into binary code (machine code) and turns it into useful information that a user can easily understand, and then the computer will understand the instructions and do what is needed. History of computersEdit The Jacquard loom was one of the first programmable devices. Definition A computer is an electronic machine which helps solving problems quickly and easily.It solves problems according to instructions given to it by the computer user. Invention The computer was invented by Charles Babbage. It is a digital machine used in all fields. Automation Humans have a problem with maths. To show this, try doing 584 x 3,220 in your head. It is hard to remember all the steps! People made tools to help them remember where they were in a maths problem. The other problem people have is that they have to do the same problem over and over and over again. A cashier used to make change every day in her head or with a piece of paper. That took a lot of time and people made mistakes. So people made machines that did those same things over and over. This part of computer history is called the history of automated calculation, which is a fancy phrase for the history of machines that make it easy for me to do this same maths problem over and over without making mistakes. The abacus, the slide rule, the astrolabe and the Antikythera mechanism (which dates from about 150-100 BC) are examples of automated calculation machines. Programming Main page: Computer programming Some people did not want a machine that would do the same thing over and over again. For example, a music box is a machine that plays the same music over and over again. Some people wanted to be able to tell their machine to do different things. For example, they wanted to tell the music box to play different music every time. They wanted to be able to program the music box- to order the music box to play different music. This part of computer history is called the history of programmable machines which is a fancy phrase for The history of machines that I can order to do different things if I know how to speak their language. One of the first examples of this was built by Hero of Alexandria (c. 10–70 AD). He built a mechanical theater which performed a play lasting 10 minutes and was operated by a complex system of ropes and drums. These ropes and drums were the language of the machine- they told what the machine did and when. Some people argue that this is the first programmable machine.[1] Most historians agree that the castle clock, an astronomical clock invented by Al-Jazari in 1206, is the first known programmable analog computer.[2] It showed the zodiac, the solar and lunar orbits, a crescent moon-shaped pointer travelling across a gateway that made some doors to open every hour,[3][4] and five robotic musicians who play music when levers hit them. The length of day and night could be changed (AKA re-programmed) every day in order to account for the changing lengths of day and night throughout the year.[2] Ada Lovelace is considered to be the first programmer.[5][6][7] The Computing Era At the end of the Middle Ages, people in Europe thought math and engineering were more important. In 1623, Wilhelm Schickard made a mechanical calculator. Other Europeans made more calculators after him. They were not modern computers because they could only add, subtract, and multiply- you could not change what they did to make them do something like play Tetris. Because of this, we say they were not programmable. In 1801, Joseph Marie Jacquard used punched paper cards to tell his textile loom what kind of pattern to weave. He could use punch cards to tell the loom what to do, and he could change the punch cards, which means he could program the loom to weave the pattern he wanted. This means the loom was programmable. Modern computers were made when someone (Charles Babbage) had an idea. He wanted to make a machine that could do all the boring parts of math, (like the automated calculators) and could be told to do them different ways (like the programmable machines.) Charles Babbage was the first to make a design of a fully programmable mechanical computer. He called it The Analytical Engine.[8] Because Babbage did not have enough money and always changed his design when he had a better idea, he never built his Analytical Engine. As time went on, computers got more and more popular. And that stands out at the beginning. This is because people get bored easily doing the same thing over and over. Imagine spending your life writing things down on index cards, storing them, and then having to go find them again. The U.S. Census Bureau in 1890 had hundreds of people doing just that. People got very bored and very frustrated, and would say, There HAS to be an easier way to do this. Then a clever person worked out how to make machines do a lot of the work. Herman Hollerith figured out how to make a machine that would automatically add up information that the Census bureau collected. The Computing Tabulating Recording Corporation(which later became IBM) made his machines, and everyone was happy. At least, they were happy until their machines broke down, got jammed, and had to be repaired. This is when the Computing Tabulating Recording Corporation invented tech support. Because of machines like this, new ways of talking to these machines were invented, and new types of machines were invented, and eventually the computer as we know it was born. Analog and Digital ComputersEdit In the first half of the 20th century, scientists started using computers, mostly because scientists had a lot of math to figure out and wanted to spend more of their time thinking about the secrets of the universe instead of spending hours adding numbers together. For example, if they had to launch a rocket ship, they needed to do a lot of math to make sure the rocket did not blow up. So they put together computers. These computers used analog circuits, which made them very hard to program. Then, in the 1930s, they invented digital computers, which made them easier to program. High-scale computers Scientists figured out how to make and use digital computers in the 1930s and 1940s. Scientists made a lot of digital computers, and as they did, they figured out how to ask them the right sorts of questions to get the most out of them. Here are a few of the computers they built: Defining characteristics of some early digital computers of the 1940s (In the history of computing hardware) NameFirst operationalNumeral systemComputing mechanismProgrammingTuring complete Zuse Z3 (Germany)May 1941BinaryElectro-mechanicalProgram-controlled by punched film stockYes (1998) Atanasoff–Berry Computer (US)mid-1941BinaryElectronicNot programmable—single purposeNo Colossus (UK)January 1944BinaryElectronicProgram-controlled by patch cables and switchesNo Harvard Mark I – IBM ASCC (US)1944DecimalElectro-mechanicalProgram-controlled by 24-channel punched paper tape (but no conditional branch)No ENIAC (US)November 1945DecimalElectronicProgram-controlled by patch cables and switchesYes Manchester Small-Scale Experimental Machine (UK)June 1948BinaryElectronicStored-program in Williams cathode ray tube memoryYes Modified ENIAC (US)September 1948DecimalElectronicProgram-controlled by patch cables and switches plus a primitive read-only stored programming mechanism using the Function Tables as program ROMYes EDSAC (UK)May 1949BinaryElectronicStored-program in mercury delay line memoryYes Manchester Mark 1 (UK)October 1949BinaryElectronicStored-program in Williams cathode ray tube memory and magnetic drum memoryYes CSIRAC (Australia)November 1949BinaryElectronicStored-program in mercury delay line memoryYes EDSAC was one of the first computers that remembered what you told it even after you turned the power off. This is called (von Neumann) architecture. Konrad Zuses electromechanical Z machines. The Z3 (1941) was the first working machine that used binary arithmetic. Binary arithmetic means using Yes and No. to add numbers together. You could also program it. In 1998 the Z3 was proved to be Turing complete. Turing complete means that it is possible to tell this particular computer anything that it is mathematically possible to tell a computer. It is the worlds first modern computer. The non-programmable Atanasoff–Berry Computer (1941) which used vacuum tubes to store yes and no answers, and regenerative capacitor memory. The Harvard Mark I (1944), A big computer that you could kind of program. The U.S. Armys Ballistics Research Laboratory ENIAC (1946), which could add numbers the way people do (using the numbers 0 through 9) and is sometimes called the first general purpose electronic computer (since Konrad Zuses Z3 of 1941 used electromagnets instead of electronics). At first, however, the only way you could reprogram ENIAC was by rewiring it. Several developers of ENIAC saw its problems. They invented a way to for a computer to remember what they had told it, and a way to change what it remembered. This is known as stored program architecture or von Neumann architecture. John von Neumann talked about this design in the paper First Draft of a Report on the EDVAC, distributed in 1945. A number of projects to develop computers based on the stored-program architecture started around this time. The first of these was completed in Gre
Posted on: Sun, 02 Nov 2014 17:23:02 +0000
Trending Topics
© 2015