Computer Basics: What is inside a computer?

Computer Basics, Hardware Issues

Question: Most of the stuff you write about is geared to intermediate or advanced computer users. How about some basic stuff for beginners? There are a lot of us folks just starting out who need information just for beginners. –Bryan

Answer: This is a project I have been meaning to do for some time. While some of the more intermediate or advanced users may find it overly simplistic, I think it will be a useful reference in teaching folks who are just beginning to use computers.

From time to time, I will try to run columns about computer basics.

Let’s start here and now, with a definition of what a computer is, and then we’ll look at a few key components inside.

A computer is a counting machine. Modern-day computers process information in the form of binary numbers. Binary is a counting system that uses the numbers one or zero (and not zero through nine). A computer is really a glorified calculator that can do millions of binary calculations a second. These binary calculations together form commands. These commands, all grouped together, tell the computer to do tasks. Programs can contain millions of commands that have the ability to take information from a computer user and do something with it to produce a useful result.

There are typically

two types of computers: those built by Apple Computer, called Macintoshes or “Macs,” and those referred to as personal computers or “PCs”. PCs were originally designed by IBM and are still occasionally referred to as “IBM compatibles”.

Today’s PCs have a variety of different parts, but the majority use Intel processors, which are controlled by an operating system called Microsoft Windows. An operating system is the program (another word for software, as opposed to hardware which is the actual parts you can touch) that controls the computer. PCs use Microsoft Windows. Macs use the MacOS operating system. Programs for Macs do not run on PCs. As a general rule, programs for PCs do not run on Macs. (There is a program called an “emulator” you can use to make PC programs run on a Mac.)

So what is a computer made up of? Lots of things, of course, but here are three main components:

  • CPU or Processor — A CPU or central processing unit, also known as just a “processor,” is the brain of a computer. It does all the binary calculations to make programs run. You’ll hear people talk about a “Pentium” or “Athlon” or (in the Mac world) “G3”. They are referring to the brand of processor in the computer.
  • Hard Drive or Hard Disk (or sometimes even “HDD” – Hard Disk Drive) — A hard drive is a special storage device on a computer that contains all the information needed to operate a computer, including programs, data created by a computer user, and the operating system. A hard drive is sometimes referred to as a “hard disk”. It is not that gray or taupe box that all the computer components are in. A hard drive is actually a bunch of disks inside a metal case. They spin incredibly quickly and special “heads” read and write information onto the disks.
    The heads are similar in concept to the arm on a record player. They move back and forth over the surface of the disks as they spin. They use magnetism to read and write binary information, which is one big reason why you should keep magnets away from your computer.
  • RAM — RAM is short for Random Access Memory. This is also referred to as simply “computer memory”. This is where the computer does short term tasks. When a program starts and runs, a copy of it moves off the hard drive and into the processor. Then, when the processor wants to accomplish special calculations or do specific tasks, it sends the task to the memory where calculations are made. When that’s done, the task is wiped out of RAM. (For more about how to add memory to your computer, please see our RAM Upgrade FAQ.)
  • If you “run out of memory”, it means that there are too many tasks in RAM for any more to fit. Also, sometimes more than one task will attempt to use the same part of the memory, and this can cause a computer crash. A crash means the computer stops working. When you switch off the computer and restart it, the RAM is “emptied” and, presuming your crash was related to your having run out of memory, the computer should operate normally again. (A hard drive is not wiped clean during a restart. It retains all information even when the computer is switched off.)

Obviously, you know there are more parts to your computer, but now you’ve dipped your toe into the water!