Jumat, 16 Oktober 2009

KINDS OF COMPUTER

"desktop computer" is a small machine which is usually accompanied by a screen (which is not part of the computer) and used at a household. "Laptop computers" are portable computers that are commonly used for work or personal media purposes. Both laptops and desktops are considered personal computers. "Mainframes" are large computers used for managing businesses or hosting servers. "Embedded computers" are computer systems that cannot be programmed by the user because they are preprogrammed for a specific task and are buried within the equipment they serve. For example, in mobile phones, automatic teller machines, microwave ovens, CD players and cars.

[change] Common uses of home computers

[change] How computers work

Computers store data and the instructions telling them what to do with the data as numbers, because computers can do things with numbers very quickly. These data are stored as binarysymbols (1s and 0s). A 1 or a 0 symbol stored by a computer is called a bit, which comes from the words binary digit. Computers can use many bits together to represent instructions and the data that these instructions use. A list of these instructions is called a program and stored on the computer's hard disk. Computers use memory called "RAM" as a space to carry out the instructions and store data while it is doing these instructions. When the computer wants to store the results of the instructions for later, it uses the hard disk.

An operating system tells the computer how to understand what jobs it has to do, how to do these jobs, and how to tell people the results. It tells the electronics inside the computer, or "hardware", how to work to get the results it needs. This lets most computers have the same operating system, or list of orders to tell it how to talk to the user, while each computer can have its own computer programs or list of jobs to do what its user needs. Having different programs and operating systems makes it easy to learn how to use computers for new things. When a user needs to use a computer for something different, the user can learn how to use a new program.

[change] Computers and the Internet

One of the most important jobs that computers do for people is helping with communication. Communication is how people share information. Computers have helped people move forward in science, medicine, business, and learning, because they let experts from anywhere in the world work with each other and share information. They also let other people communicate with each other, do their jobs almost anywhere, learn about almost anything, or share their opinions with each other. The Internet is the thing that lets people communicate between their computers.

[change] Computers and waste

A computer is now almost always an electronic device. It usually contains materials that will become toxic waste when disposed of. When a new computer is bought in some places, laws require that the cost of its waste management must also be paid for. This is called product stewardship.

Computers can become obsolete quickly, depending on what programs the user runs. Very often, they are thrown away within two or three years, because newer programs require a more powerful computer. This makes the problem worse, so computer recycling happens a lot. Many projects try to send working computers to developing nations so they can be re-used and will not become waste as quickly, as most people do not need to run new programs.

[change] The main hardware in a computer

Computers come in different forms, but most of them have a common architecture.

  • All computers have a CPU
  • All computers have some kind of data bus which lets them get inputs or output things to the environment.
  • All computers have some form of memory. These are usually chips (integrated circuits) which can hold information.
  • Many computers have some kind of sensors, which lets them get input from their environment.
  • Many computers have some kind of display device, which lets them show output. They may also have other peripheral devices connected.

A computer has several main parts. When comparing a computer to a human body, the CPU is like a brain. It does most of the 'thinking' and tells the rest of the computer how to work. The CPU is on the Motherboard, which is like the skeleton. It provides the basis for where the other parts go, and carries the nerves that connect them to each other and the CPU. The motherboard is connected to a power supply, which provides electricity to the entire computer. The various drives (CD drive, floppy drive, and on many newer computers, USB drive) act like eyes, ears, and fingers, and allow the computer to read different types of storage, in the same way that a human can read different types of books. The hard drive is like a human's memory, and keeps track of all the data stored on the computer. Most computers have a sound card or another method of making sound, which is like vocal cords, or a voice box. Connected to the sound card are speakers, which are like a mouth, and are where the sound comes out. Computers might also have a graphics card, which helps the computer to create visual effects, such as 3D environments, or more realistic colors, and more powerful graphics cards can make more realistic or more advanced images, in the same way a well trained artist can.

[change] References

  1. Heron of Alexandria. Retrieved on 15 January 2008.
  2. 2.0 2.1 Ancient Discoveries, Episode 11: Ancient Robots, History Channel. Retrieved on 2008-09-06
  3. Howard R. Turner (1997), Science in Medieval Islam: An Illustrated Introduction, p. 184, University of Texas Press, ISBN 0-292-78149-0
  4. Donald Routledge Hill, "Mechanical Engineering in the Medieval Near East", Scientific American, May 1991, pp. 64-9 (cf. Donald Routledge Hill, Mechanical Engineering)
  5. Don't confuse the Analytical Engine with Babbage's difference engine which was a non-programmable mechanical calculator.
  6. B. Jack Copeland, ed., Colossus: The Secrets of Bletchley Park's Codebreaking Computers, Oxford University Press, 2006

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