How Computers Work

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How Computers Work

مُساهمة  Mahmood في الأربعاء أكتوبر 04, 2006 2:57 pm

How Computers Work


Every one of us needs help to get his work done, and every one wants his work to be done very fast. People from the old times tried to make the life easy and started to invent materials to help them to make their work become easier. They started with stone knives, stone swords, to metal cooking fries and finally they invented computers.
What makes the invention of the computer truly revolutionary is that while most previous inventions improved human welfare by amplifying the physical power of the human body to manipulate its environment, computers amplify the power of the human mind itself, making possible the manipulation and storage of information on a scale never previously possible. For example, scientific calculations that would have taken decades for scientists to complete with pen and paper alone can now be completed in minutes by modern computers.
So what are computers, and how do they work? What is the future of computers? Are they becoming more and more necessary in human life?
All these questions and more will be answered in this report.


“A device that computes, especially a programmable electronic machine that performs high-speed mathematical or logical operations or that assembles, stores, correlates, or otherwise processes information”. (

As we can see from the definition we can imagine that computers are pieces of metal that do the calculations very fast. It’s quite right to say that but it more than that. Let me explain what I mean. Now we have a fast machine that do the four main calculations (Add, Subtract, multiply and divide) what we need now is something can control, manage and benefits from this speed and here when we invent the software. Despite the computer’s reputation as a smart machine, it is in fact, very stupid. It is capable of performing only very simple operations – for example, adding two numbers together or determining which number of a pair is larger. But, what makes computers powerful, in spite of this fundamental stupidity is that these operations are performed very, very fast, and without error. By combining many simple operations in the right way, a human can get a computer to perform extremely complex calculations.

Now let’s take a close look inside a computer:)

As we can see in the diagram, computers made of many different components which make it work faster and add more functionality to it.

For example motherboard circuit is one of the most important in the computers. It have own memory which it called “cache memory”. This circuit can be build in different components such as sound card, video card and ether net card which makes the computer cost in total cheaper.


Now let’s talk more deeply on how the computers really work and the different components inside the PC.


1.1 Motherboards
A modern computer is composed of many different, highly specialized components, which need to be somehow connected to form a single working whole. It is the motherboard that provides the physical substrate for these components, and that provides the circuitry coordinating these components and enabling them to communicate with each other. Motherboard is the main board in computers. The purpose of this board is to connect other expansion cards such as the Sound card and the Video card. Motherboard contains many chipsets for adding different functionality. It also contains the slots for expansion cards, so that you can add many different cards. The motherboard connects all the cards together in one board, so it does the operations very fast.

1.2 Processors CPU (Central Processing Unit)

It’s also called the heart of the computer and its brain. Millions of transistors do the calculations very fast. The actual microprocessor is very small - it’s even smaller than a penny. The Microprocessor is the most expensive part on the computer.
The Microprocessor divided into three main parts:

1. Control Unit (CU):

It’s almost as the manger in the real life. It controls all the operations in the Processors and gives the instructions and the order to the ALU and to the registers. It’s control all the operation and make sure that everything works fine into the processor.

2. Arithmetic Logic Unit (ALU):

The ALU is the calculator which performs basic arithmetic and logic calculations very fast, and performs all the manipulation of data in the CPU registers.
The ALU takes the input from the control unit to be operated and indicated which operation to use for this input. It’s also provided the result of computation as an output and sends this result to the registers. (

3. Registers:

It’s a memory build in CPU it’s also called the “cache memory”. This memory is very fast. It accesses by CU and ALU. Its static memory, which means it’s a volatile memory, loses the data after the power is shut off. The purpose of building this memory in the CPU is to store the finished operation from the ALU and the CU. (See FIGURE 2)

FIGURE 2: CPU Components
(SOURCE: Bronson, 1.1)
1.3 Memory and Storage Devices

One of the main requirements for any information-processing system is the capacity to store information. In modern computer systems, both instructions and the data they manipulate are stored in main memory. In general, there is a tradeoff between the size of a type of memory and the speed at which it is accessed. The most important distinction is between memory and storage. Though these two terms are often used interchangeably, computer scientists use ‘storage’ to refer to high capacity, non-volatile devices with comparatively slow access-speeds, such as hard drives, while ‘memory’ is used to refer to devices that are volatile, with much lower capacity, but whose contents can be accessed much more quickly.
In the old days there were no storage devices at all. But when the technology started to become more powerful, and the operating system gained more functionality the need of storage devices become more important in the computer industry. First, they stored all the operating system on a Punch Card (See FIGURE 3), but that wasn’t big enough to store the new operating systems. So they started to produce bigger storage devices. They first started with the ROM then 5.¼ “floppy disks, after that 3.½ “floppy disk. Then they started to produce hard drives which have much more capacity. There are much kind of the Storage devices such as CD (Compact Disk), DVD and much more.

FIGURE 3: Punch Card

1.4 Different Kind of Memory

In general memories are very fast storage devices. They help the computer to work faster.
The problem with memories is that it can not hold bigger sizes of data. Obviously bigger capacity of memories on the computer it’s increase the performance of the computers

There are three main memories:

1. ROM (Read Only Memory):

A small capacity type of memory that can handle the basic program to let the computer works this program called BIOS (Basic Input Output System). ROM is non volatile memory, meaning it doesn’t lose its data when the computer is turned off. These days they replace the regular chipset of memory to flash one which it have many futures. The regular user can’t write on this memory. It’s just to let the computer go on.

2. RAM (Random Access Memory):

This memory is bigger in size compared to the ROM. The purpose of this memory is to let the operating system work and load on this memory. RAM is a volatile type of memory, meaning the data it contains is lost when the power is shut-off. The RAM in different computers varies in storage capacity and comes in several varieties such as: DD-RAM, RD-RAM and SD-RAM.

3. Cache Memory:

One of the bottlenecks in modern computing is the slow speed at which information from main memory is accessed. Cache memory attempts to counter this problem by placing a small amount of very fast memory very close to the CPU.
A very fast memory it builds next to into the processor because its need less time to access to the processor. The purpose of this memory is to help sending the data from the processor to the RAM when the data processed and the other way from RAM to the processor when the data need to be process.
(Thompson, 191-219)

1.5 Expansion cards

These cards are to help the computer do more jobs and let the computer have more functionality. There are many examples of expansion cards such as: Video cards, Sound card, SCSI card (this card allowed the user to add SCSI hard drive which always have more capacity and much faster than the regular storage devices), Ethernet card (for network and the internet), modems and expansion cards to let the user add more USB ports and much more. (D. Dacey, July 28)


After we read a good review how make the computers work and the most important pieces on the actual computer that without these devices the computers not going to work, lets see now how this all devices work together to let the computer works.

2.1 The first click on the power POST (Power on Self Test):

When the user clicks the power button, he feeds each component with electricity and one of the hardware that work first is ROM (Read-Only-Memory). ROM contains a small program called BIOS whose responsibility is to do a fast scan of the computer called POST.

The purpose of POST is to make sure that different components are in their places, so it sends an electric signal to the RAM (Random Access Memory), Keyboard, VGA (Video Graphics Array), and to the storage devices to make sure they are sitting properly inside the computer and are ready to go. If the POST find something wrong with one of these devices it will send beep sound, using different beeps sounds to indicate different devices So actually you can know what the problem is from hearing the beep sound.

When it finishes checking each device to make sure that everything works fine, it starts to locate from where is going to boot the operating system. The boot process might take seconds if you have small operating system such as MS-DOS (Microsoft Disk Operating System), or it take a little more time if you have an operating system such as Linux or Windows XP. (D. Dacey, July 21, 2004)

2.2 The shutdown process

You get tired from sitting on the computer for a long time and now it’s time to relax. To turn off the computer, simply click on the power and that’s make sure that the computer shut down. But that was in the past in the old operating system. These days the operating system getting more complicated and more safety and powerful to let the user save the work before it shut down.

Let’s take Windows XP as an example; if you tried to shut down Windows and one of the programs is still working, such as a word processor or anything else, it will ask you if you want to save the changes. Now the shutdown process becomes more safe and powerful for the user.

But what really happen inside the computer when you click the shutdown or the power off? Well, all devices inside the computer lose the power which makes the circuits in the motherboard and other hardware “open circuits”, which make the computer turn off.
(Khaled Ismail, personal communication)

2.3 Input \ Output

To control all the devices in the computer and ask the computer to do the operation that it suppose to do we order him in different way and this orders come from the input and the output.
Input devices are: devices that input the signal (analog or digital) to the computer examples to input devices are: keyboards, mice, laser pen, scanner microphone joystick controller and even piano pad.
Output devices are: devices that output the signal (digital or hard copy) to the user examples for output devices are: monitors, printers and speakers.

2.4 Network \ Internet

As companies grow bigger and bigger, the needs of more computers to be connected together become important, to let the employer save the time when they send files to each other. Networking between become the amazing solution for this problem. They connected many computers to each others and they start to share files as fast as 10 Mega per second.
Internet almost the same idea as networking, it becomes the most reliable, faster and the easiest way to send a message from the east of the earth to the west. Internet becomes most popular communication between the people from the different countries and even contents.


A machine as powerful as a computer can do almost anything that a human could ask for, from sending a rocket to the moon, to calculating a huge database in seconds, and even to teaching children basic math.
So what the future for computers and how much can go farther?

Although for the past thirty years the number of transistors on a chip and therefore the processing power of that chip have been increasing exponentially, continuing this rate of increase is becoming more challenging and will eventually bump up against constraints set by the laws of physics itself.

3.1 EUVL Chip making (Extreme-Ultraviolet Lithography):

As we mentioned in the beginning the processor is the most important part in the computer, scientist looking forward to produce a new kind of processor faster than what we have at this moment three times. This processor can reach speed of 10 to 15 GHz (Giga Hertz) which faster at least three to four times than the newest most technologist silicon processor. EUVL will be extremely useful because of using more and more transistors into the chip.

This technology will be released in 2007 and all computers are going to be powerful fast machines.

3.2 Replacing the electricity parts to DNA cells:

Do you get tired of hearing the message saying “Not enough space in your hard drive”?
If the answer is ‘yes’ then we have the solution. Scientists are looking forward to producing an amazing solution for this problem, they are trying to replace all the electrical part in the computer to a “DNA” cells which perform fast calculation and bigger capacity in your computer if we can still call it “Computer”. This capacity can hold up to 10 terabytes which means more a hundred times capacity than the regular hard drive.

This future will be a point of a new era in the computer filed because it will be much smaller for example “…more than 10 trillion DNA molecules can fit into an area no larger than 1 cubic centimeter”. This future will help to do faster calculations and do the most complex calculations in hours which it takes months and even years with the most powerful computer we have these days. (Kaku, [insert page numbers])


In conclusion, computers have become much more powerful and useful machines to their users. They are everywhere: in your car, in your kitchen - and even in your hand and with your children to play with.
It’s hard to guess the future of computers and how it will be. Powerful machine such as computers can be dangerous if it didn’t use in a proper way.
Computers have a bright future and the uses of this machine might replace of people and this might be a problem.
مــــديــر الـــمــنــتــدى

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تاريخ التسجيل : 09/09/2006

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مُساهمة  بــــــــنت العــــــــز في الإثنين أكتوبر 09, 2006 3:34 am

KEEP IT UP>>>>>>>sunny Rolling Eyes

وما من ناقل إلا سيفنا ويبلا ويبقي الدهر ما نقلت يداه
فلا تنقل بكفك غير شيء يسرك في يوم القيامة أن تراه
بــــــــنت العــــــــز
^*~. أول الواصلين .~*^
^*~.  أول الواصلين .~*^

عدد الرسائل : 138
تاريخ التسجيل : 03/10/2006

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