I'm going to attempt to do something that, until just recently, I would have thought was impossible. I'm going to explain, in a very elementary way, how a computer works.
Knowing this isn't going to help you save a life or avert a war, nor will it help you balance your checkbook or play a video game.
But when you see how logical and simple--how unmagical--a computer's innards are, you'll be a lot less intimidated by smooth-talking salesmen and less wowed by some television commercials about computers.
That's not to say computers are a Madison Avenue hype job. Rather, it's simply to prove to you that there's no reason to feel awed by a computer.
Together, five elements make any tiny desktop computer and the giant mainframe jobs do what they do.
1. Input: This is the point where you, the user, communicate your desires and instructions to the computer--for instance, via the computer's keyboard or by inserting a preprogrammed diskette in a disc drive.
2. Memory: This is where the computer stores the input. An example: here the computer will store any instructions you may provide on how it is to accomplish what you want done. The memory also is where the computer stores the raw data you would like manipulated.
3. Arithmetic Unit: You quessed it. Here the computer performs all calculations necessary to accomplish its task.
4. Output: This is where you are going to get the answer to your problem. Output can be flashed on a television monitor screen or printed out on paper, or it can even come via the spoken word, since there are now programs and gadgets that make it possible for a computer to mimic the human voice.
5. Central Processing Unit, or CPU: The "boss" of the computer. The CPU takes your instructions and raw data and files it in the computer's memory. And, when you order it to, it will follow your instructions on how it is to go about its task. The CPU also sees to it that the result finds its way to the output point so you can get your answer.
Essentially, those five elements are the cogs and wheels of a computer. The potential for problem solving is there, but unless the computer is given specific instruction, it's just going to sit there as a mighty expensive piece of untapped potential.
Say you just want to add two and two. Behind that simple calculation lies a logical sequence of steps that are the same whenever you add one number to another. (A) You identify the first number. Then you (B) identify the second. Now you (C) tell the computer to (D) add the second number to it. Then you (E) instruct it to display, print or tell you the result.
Very basic. But that's what you have to tell the computer to do before it can add two and two--or 9,322.09 to 46.991, for that matter.
Now enter the CPU and the computer's memory.
A computer has thousands, if not millions, of individual memory units. Each memory unit is called a byte and each byte has a unique location--or "address"--within the computer's memory.
When you "input" your commands, the CPU files them sequentially in the memory so that the first part of the instruction (in this case instruction "A" as defined above) goes in, say, byte No. 1, while the next part ("B") is slipped into byte No. 2 and so on. That way, when the CPU later is told to follow the instructions, it doesn't get lost.
In addition to telling the CPU how to add two numbers, instructions will also give the CPU the addresses of unused bytes of memory where raw data (your "2s" and "9,322.09s," for instance) can be filed until needed.
So, when you tell the computer to "run"--that is, follow the instructions--it will go to byte No. 1 where it has filed instruction "A" and perform the first step. Then it will go to byte No. 2, the address of instruction "B," and perform that step.
Until, finally, you see the answer to 2 plus 2 displayed on your screen.