COMPUTER BASICS

WHAT IS A COMPUTER?

The dictionary definition says a computer is "an electronic machine for making calculations", but a lot of the tasks we perform on a computer, like e-mail and word processing don't seem to involve much calculating.  So, just what is a computer, anyway?  Let's make our own definition.  A computer is a machine for processing and storing information electronically.  Add to that a way to get information into the computer in the first place, and some way to get it out afterwards so we can look at it and presto, we have ourselves a general-purpose computer.  Altogether it has four basic parts or functions:

  1. Input
  2. Processing
  3. Storage
  4. Output

Input - What ware some ways to get information into a computer?  One of the more obvious ones is the keyboard.  Each time you press a key, that information is sent over the keyboard cable into the computer.  Another is the mouse, every movement of the mouse and every click of the mouse button is information going into the computer.  When we want to get a lot of information into the computer, we would use a floppy diskette, or a CD.

Processing - If we only put information into the computer and took it out later in the same form, computers could be much simpler.  Much of the time though, we want to do something with it first.  Doing something with it is called processing, and most of this takes place, in the part of the computer called the Processor.

Storage - The part of the computer that stores data even when turned off is called the Disk Drive.  Drives can store enormous amounts of data, and of course the data is saved even when the power is off.  The only problem with disks is that by computer standards they are somewhat slow.  There is another method of storage called RAM, however RAM needs power at all times, and when the computer is turned off, all of the data stored in the RAM is lost.

 Output - Data in our computer is useless unless we could get the data back out so we can see it and use it.  When you are using a computer, one form of Output is usually right there inform of your face.  The monitor has a screen that shows you information, and anything that makes the computer's information available to you is an Output Device.  Another output device is a Printer.
Input / Output - Some device work both as Input and Output.  An example of this is a Floppy Drive.  You can have the computer put out data onto a floppy disk, and then take that floppy disk to another computer and use the data as input.  If your computer is connected to a phone line, data will be going in and out on the same line, so the modem must be an input and output device at the same time.  The computer's input and output together is called Input/Output, abbreviated as I/O.

Software - The physical parts of the computer that we've been talking about so far are called Hardware, because you can see and touch them.  These hardware devices can input and output data, they can process data in all sorts of ways, and they can store data.  How does this computer hardware know what to do, and when to do it?  The fact is, these hardware devices don't have a clue.  They need instructions to tell them what to do.  These software instructions are called Programs or applications.  A software program is a sets of instructions to do a particular task.  For instance, if you want to play a game on the computer, you must have a program that contains the instructions for that game.  If you want to write a letter, you would use a program for word processing, and for e-mail, an e-mail program.

One program, called the Operating System, actually runs the computer.  Certain things need to be done no matter what you are using the computer for.  These are things like moving data on an doff the disk, putting information on the monitor screen, and so forth.  If every program needed to contain the instructions for doing all these things, it wouldn't be very efficient.  So, with the operating system taking care of the details, each of the other programs can stick to their particular jobs.  So, the software on your computer consists of the operating system to run the show, and applications for each of the things you actually want to use your computer for.

Digital and Analog - There are two ways to represent information, Digital and Analog.

Analog is any piece of information that can have different values; no limit. For example: time, temperature, and speed of your car can all have a continuous range of values. So while it is 55 degrees outside, it could really be 55.12492 degrees, or any value between that and 55. Digital information is restricted to be specific; a limit. For example, a traffic light is red, yellow or green; not "yellow-green" or orange. Computers use a form of digital information called binary information. Here, the information is restricted to only two values: one or zero.

You can also think of something that is Analog if it has moving parts, while Digital does not contain moving parts but some kind of processing unit.

Binary

The Mathematics of Computing

Humans represent numbers using decimal notation: that is, each digit can have one of ten values, zero through nine. This is also called “base 10 or power of 10's” mathematics. Binary information uses only ones and zeros , which would be “base 2 or power of 2's” mathematics. Just as with regular numbers (decimal) you start at 0, count to 9, and then reset the 9 to a 0 and add a 1 in the "tens" place, with binary information you start at 0, count to 1, then reset the 1 to a 0 and add a 1 in the "twos" place. So binary counting goes like this: 0, 1, 10, 11, 100, 101, 110, 111, 1000, etc.

The number 111 is the binary equivalent of the decimal number 7. How? Just as 111 in decimal means 100 (10 to the second power) plus 10 (10 to the first power) plus 1, in binary 111 is 4 (2 to the second power) plus 2 (2 to the first power) plus 1, which is 7. As you can see, binary numbers can get pretty long. For example, the number 181 in decimal is 10110101 in binary.  Everything your computer does is in binary then, you will start seeing that everything is measured by it like memory, hard drives, processors, and file sizes are just a few.