How does a computer work ?

Answer 1

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we first have to examine what it really means for a system or device to be "digital". All being digital means is that a system stores and operates on information in a very specific way. In a digital system, every piece of information is stored in a bit (or multiple collections of bits). A bit is a variable that can have only one of two values: it can either be a 1, or be a 0. The easiest way to think of a bit is as a container - this container is either completely full or completely empty, but never anything in between. A full container can be thought of as a 1, an empty container as a 0.

The beauty of this is that any piece of information can be represented as a collection of bits. The way this is done is by making each bit the answer to a yes or no question. For example, lets say I wanted to know whether a person has long hair or not. I could represent this piece of information by deciding that if the person has long hair, I will set a certain bit to be a 1. If the person doesn't have long hair, I will set that same bit to be a 0. As long as you followed the same convention, you could look at the same bit that I just set and know whether the person has long hair or not, even if you had never seen them before.


So what does this have to do with computers?
The fact that a computer is digital means that it (or any other digital system for that matter) can really only do three things:
Set a bit to be 0
Set a bit to be 1
Look at the value of a bit and use it to decide what value to give some other bit.
So how do computers do all of these complex and wonderful things that they do? Well, computers look at and manipulate millions and millions of bits. Each one of those bits is assigned a certain meaning, in a certain context. When you tell a computer to do something, all that is really going on is you are setting certain bits in a certain way, and the computer interprets those bits to figure out what you want it to do. It's important to understand that the bits in and of themselves have no real meaning - it's only by assigning meaning to them that we can interpret the information they contain.
Because computers operate on such enormous numbers of bits, we group bits together and gives these groups their own names. A "byte" is simply a group of 8 bits. A kilobyte is about one thousand bytes, a megabyte is about one million bytes, and a gigabyte is about 1 billion bytes.

The Three Subsystems of a Computer
Now that we understand what a digital system and bits are, we can split a computer up in to three main subsystems:
CPU
The Central Processing Unit, otherwise known as the CPU, looks at certain bits to determine what its being told to do, and once it has figured that out it performs that operation. The CPU is the heart of the computer - it does all the interpretation and manipulation of bits.
Memory
Memory does exactly what its name implies - it remembers the values of bits. It can either store bits sent to it by the CPU or return the values of those bits back to the CPU. Hard disks and RAM are really just two different kinds of memories; they both perform the same function, they just use different physical mediums to do so.
Input/Output
The Input/Output (I/O for short) subsystem also does exactly what its name implies - it takes from the outside world and sends them to either the memory or the CPU, and it also takes bits and sends them back out. The keyboard and the screen are part of the I/O subsystem.
Input/Output
There are an incredible number of I/O devices out there, but we'll take a look at the common ones:

Keyboard - translates each key that you press in to a series of bits, which the CPU can decipher to figure out what you typed.
Mouse - translates movements and button clicks in to bits as well, which are once again sent in to the CPU.
Monitor - translates bits sent to it into shapes and colors you can see on the screen.
Network card - translates bits in to electrical signals and sends these signals down a cable, so that other computers can receive these signals and retranslate them in to bits. This allows computers to communicate with each other.
As you can see, each I/O device is basically a translator, it either translates physical things in to bits or vice versa.

Memory
Because computers operate on such enormous numbers of bits, they need memory in order to keep track of all these different bits. There are two major categories of memory components:
Random Access Memory - RAM
The best way to think of RAM is as being a huge matrix, where each cell in the matrix holds one bit. Physically, RAM's are just chips which implement this matrix. The analogy of bits being containers actually holds very well for RAM's: each of one of these cells in the matrix really is a container, or "bucket". This bucket (which is called a capacitor) stores electrical charge, and the bucket is always either full or empty, storing either a 1 or a 0. The RAM's buckets are actually leaky - this means that full buckets need to be periodically refilled. For this reason, when you turn a computer off, all data stored in the RAM is lost; it just leaks away.
RAM is named the way it is because it is supposed to signify that you can "randomly access" any bit in the matrix at any time.
Disk Drives
There are several different types of disk drives, but here are the major ones:
Hard Disk - uses a spinning magnetic platter(s), bits are stored in the magnetic field of this platter. Hard disks can store enormous amounts of data (40 gigabytes or more), but it is a lot slower to access them than it is to access RAM. They also don't lose their value when the power is turned off.
Floppy Disk - similar to a hard disk, just a lot less dense; they usually only store about 1.4 megabytes. Floppy disks get their name because their platter isn't made out of a hard material, but rather out of the same material that tapes are made out of.
CD-ROM - Reads bits stored on a compact disk, usually about 650 megabytes per disk. Bits are stored as grooves in the disk surface, and an optical laser is used to read the bits.
Because of the different ways memory components store bits, they all have different sizes and speeds. The speed of a memory component is the amount of time it takes for that component to read and return the requested bits or store new bits. RAM's are the fastest components, but they also generally hold the least amount of bits.
CPU
A CPU is implemented by something called a microprocessor. Microprocessors take in groups of bits that are called instructions. These instructions tell the microprocessor what it is supposed to do - which bits it is supposed to manipulate and how it is supposed to manipulate them. A program is just a sequence of instructions telling the microprocessor what to do at each step along the way. All programmers really do is generate a bunch of instructions which cause the microprocessor to perform the function they want it to.

Putting it all together
Now that we've covered the three major subsystems, we can take a look at how everything is actually put together.
All computers have whats called a motherboard - the motherboard is a circuit board that connects all of the various components together. Its main purpose is to hold the CPU and the connections between the CPU and all the other subsystems. You will usually find the RAM of the computer on the motherboard as well. Here's what a motherboard looks like:

The CPU communicates with the rest of the components with what's called a bus. In reality, a bus is just a bunch of wires and connections between the CPU and the rest of the components. These connections allow the CPU and the other components to send bits back and forth as electrical signals.
Most motherboards have places you can insert other kinds of devices. These devices are generically termed "cards", because they often have the shape of a card. Two examples are graphics accelerator cards and network cards, both of which either extend or enhance the capabilities of the computer.

Phew!
Taken as a whole, a computer is a vastly complicated machine, perhaps one of the most complicated machines built by man. Attempting to understand every single detail about every single component in a computer would probably take several lifetimes to achieve. The good news is there's no real reason to do that. Understanding the major subsystems and how they interact with each other is a lot more useful and important than the details. Understanding that a computer can and will do only exactly what it is told to do is probably the most important lesson of all.

Answer 2

I have never learnt the computer. Therefore perhaps I can tell you better untechnically.

Think of big library which is having thousands of books in sevaral almirahs, at several floors of several sections of a building.

Now if you want to look at a particular book on one good day, You will have to unlock the door of the library first. Then you will have to find out the section of the building and at which floor your almirah is wherein the book is kept

As it takes time to reach your destination and to get your book finally so does computer takes to show your desired file. Computer is not like TV which can be watched just by switching it on.

Now when you are inside the library i.e. when copm has started, you can look at other books also, likewise you can switch over to other files of comp.

Now when you want to go home what will you do ? you will not just come out of the building.You will keep the book in its shelf , close the almirah, leave the floor I, II or IIIrd and come down to the ground floor.Then you will shut the windows and lock the door of library.

It will again take some time and the comp. will also shut down similarly.

This happens when you are working with windows only.

Answer 3

A comuter does not "work" or "think" instead it does what its told to do. it just can do what its told to do really fast so you can have "complex" programs that are just paths(if this, then that). (for example:if mouse clicked, then load program) kinda stupid answer but computers are really simple when it comes down to it. and memory is all based on megnetic feilds of north and south ;). really realy simple. learn just a little of Basic programing or Qbasic and you'll under stand software in a simple way! ;) its easy to use like the command PRINT "hello!" displays "hello" on the screen! :P wOOT!! think of a light switch on/off you tell the switch what to do. faster computers allow you to have more lights and switches! computers are nothing without programs and thats where they seem come to life!

Answer 4

Normaly with 220 or 240 volt power input from a wall plug ..

Answer 5

like any other machine does...
you give the input ,feed it with electricity ,and you get the output after it "understands" the data,if not it simply says "*** error" which means "u stupid"

Answer 6

big question.

please use this link for a lot of good information:
http://computer.howstuffworks.com/pc.htm

have a nice day.

Answer 7

it doesnt silly thats your job

Answer 8

if you want to know really, go to www.howstuffworks.com

Answer 9

by switching on.

Answer 10

INPUT ------> PROCESS ------> OUTPUT