Computer Help A to Z PC Basics
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by John Anthony

What is a computer?

It is one of the most revolutionary and powerful tools ever developed! It stands in the company of the wheel, the aircraft wing and the internal combustion engine because of the tremendous changes it has and still continues to make in our lives.

Together with the its close cousins, the Internet and the web, a global, instantaneous communications network now exists in a way no one dreamed of when the first commercial PC appeared in 1981.

This Web site was developed to help non-technical people take full advantage of this powerful technology. On the surface, its workings are not at all intuitive, and probably appear somewhat mysterious. It is just the opposite! It is a very well ordered, logical machine.

Our aim is to take a some of the mystery out of it for you!

Where do we begin?

There are different ways to study any system. One is by describing each component. In Hardware each component of the PC is described to provide a basic understanding of how each one works. This type of analysis by itself doesn't provide an understanding of the how the PC functions as a unit.

In PC Basics we talk about the different functions in a PC and what they do. At the end we show you the bigger picture where they all come together to make the PC work.

  • Processor - At the heart of every PC is the central processing unit, CPU for short. The CPU plugs into a motherboard which has a lot of other chips and electronics on it. The CPU and other components work together to schedule, compute and control everything that happens in the PC.

    You've probably seen the 'Intel Inside' appearing in many computer sales ads. They are referring to the Intel CPU which is often a Pentium or Celeron processor.

  • Input - devices that allow you to direct the action of the PC. The keyboard and mouse enable you to control the computer by giving it directions (input).

  • Output - devices that display or produce results for you. The video display and printer are the primary ones. The speakers beep, chime etc., to let you know an action is completed and they also play your favorite MP3 files.

  • Memory - is temporary storage used by the CPU to store results of calculations or files brought in from the hard drive. Memory is very fast and volatile which means it loses it's information when power is removed. The memory cells are housed in Integrated Circuits (ICs), or chips as they are often called.

  • Storage - devices that retain information magnetically (Hard Disk Drive and Tapes) or optically (CD and DVD). They are not as fast as memory but can store much more data. They do not lose their information when power is removed.

  • Software - these are instructions, also known as programs or code. Software is to the CPU, what knowledge is to our human brains. The CPU and software work very closely together. Each one by itself is useless. Only when they work properly together can they direct and execute activities in the PC in a productive way.

This chart shows the components we've talked about, grouped together functionally. Arrows show how they show how they interconnect.

The PC and the ATM

What do a PC and an automated teller machine have in common? They are both computer based systems. By explaining the operation of an ATM it may help you see how information flows in a PC based system.

The PC is general purpose. It can run many different types of software that do a wide range of things.

The ATM has all the functional elements of a PC: processor, memory, storage, input, output and software. Like the PC, it can connect to remote computers using communication services in order to access your bank records and determine whether or not to authorize transactions.

The ATM can be thought of as a specialized PC that is designed to do a very limited set of operations. It takes in deposits, dispenses withdrawals and prints out account information.

The ATM software resides in a local or remote storage device and runs on a central processing unit probably a microprocessor or micro controller. It is programmed to sit and wait for you, the user, to tell it what to do.

How do you tell it what to do? With input of course. The basic inputs to the ATM are a keypad, the ATM card reader and the envelope receiver bin used to make deposits.

After the ATM has read your card and you have successfully entered your PIN (Personal Identification Number), which it temporarily stores in memory, you can complete your transaction. Let's say you want to withdraw $100. Using the keypad you select the account and the amount to be debited. The codes for the keys you press go into memory until the processor uses them to determine what action to take. During all this, how do know what the ATM is doing? You know because you are reading a display output that shows you status messages.

The processor in the ATM checks with the remote computers to determine if your bank account is active and if there are sufficient funds to proceed. If so, it slides your money out through the cash dispensing machine door which is another output device. Its then asks you by way of the display if you want to make another transaction. Based on your input it takes the proper action.

If you are done it returns your ATM card, and prints another output device a transaction receipt and closes itself up and waits until someone asks it to do something.

Hopefully you've begun to see what the basic PC functions are and how they work together to perform a useful service for us.


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Computer Help A to Z
88 Windmere Drive
Angier, NC 27501

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