"Computer Memory & Storage"

Author:  W.P. Flinn, Updated 12/7/05

    One of the most confusing things about computers, for the new computer user, is trying to figure out the difference between memory and storage.  "Does it really make a difference if I am talking about  the hard drive's storage capacity or the computer's memory?"  Yes... to a certain extent, it does.  If you are having problems with your computer and getting error messages, determining the cause of those error messages is vitally important when it comes time to describe these difficulties to your friendly computer technician, so they can get you back in business.  If you were to say, for instance... "my computer is running out of memory..." when what you mean is that the storage space (on the hard drive) is becoming filled up, you are likely to get, at the very least, a sarcastic smirk from the technician, and you won't be conveying the correct message about your computer's difficulties.  Let's take a look, then, at some of the differences, and discuss some of the terminology surrounding computer memory and storage.
 
 

Memory:

     Computers have an electronic "memory" which allows them to store program variables, program data, and various types of information  about the computer's hardware configuration.  There are various types of computer memory inside the computer, the most often talked about of which is known as Random Access Memory, or RAM.  This memory is what is known as "volatile" memory, which means that the contents of this memory gets erased when the computer is turned off.  Memory is separated into different areas such as base memory, upper memory, and extended memory.  This type of memory is usually made up of microchips placed on a small circuit board.  A single inline memory module (SIMM), or dual inline memory module (DIMM) are common forms of RAM,  the types of circuit boards shown below (see Figure 1), and are installed on the main board inside the computer.

 Each of these microchips is made up of thousands of "cells" which hold an electric charge.  These charges represent voltage levels which make up the "binary digits", or BITS, which are the basic logic units with which computers communicate.  The term "binary" simply means that there are only two possible states.  In this case, the BITS are either in the form of a "1" or a "0".   Put eight BITs together to form a "BYTE", and higher combinations of BITs form "WORDs".  All of these represent information that is in the computer's memory, and ultimately result in the information that comes out as data, pictures, and the many other things that a computer can produce.

    Another distinguishing feature of computer memory is that it is divided into specific "addresses" for each function of the computer.  When the computer's memory is storing and manipulating information concerning a certain process in the computer, it is storing the information about each process in its own unique memory location, known as the address.  If the computer wants to store information about the video system, for instance, it stores it in the memory address unique to video functions.  That way, other data is not being randomly placed in memory, but rather in an organized manner, so that the computer knows where to find this data later.

    One of the main concerns, when it comes to computer memory, is how it affects overall system operation.  Increasing the computer's memory increases its ability to handle and manipulate data, and can also help increase the speed of operation as well.  It is often said that limiting the amount of computer memory installed in a computer is like putting a speed governor on a car.
 

Storage:

    When the computer is turned off, the computer's memory is completely erased.  There needs to be a method for storing the application programs, the operating system, and data created by the user.  Rather than reloading the various application programs from scratch, for instance, the computer has a way to store these files so that they can be quickly recalled each time the computer is turned on.  Likewise, the user has to have a place to keep important data files while the computer is turned off, and quickly recall them when the computer is turned back on.  That's where computer storage comes in.  Computer storage is made up of various types of devices, some installed internally to the computer, some having the ability to be added externally as needed.

    One of the most often discussed, and most common forms of storage is the computer's hard drive.  The hard drive gets its name because it is a sealed unit with a hard "disk", or platter, installed inside which is used to store information   (see Figure 2, below).  The disk stores information magnetically, much like the way music is stored on a cassette tape, except that instead of music and sound waves being stored, binary digits are stored.  Just like in memory, these BITS represent the data from the various program and data files which are stored on the disk.   This information is stored magnetically, because this allows the information to be stored and retained, even when the computer's power is turned off.  The files can then be retrieved later, when needed, regardless of how many times the computer has been turned on or off.

 
 

 Figure 2:  Hard Disk Drive Assembly (uncovered)

 
 

    One of the most common difficulties experienced with hard disk drives is that they have a finite amount of storage space, and can become filled quite easily, especially if the user isn't performing routine maintenance on the hard drive.  Often times, when a client says they are "... running out of memory...", what they really mean is that their hard drive is becoming filled to capacity, and they are running out of storage space.  There are several ways to remedy this problem, among which is clearing off unneeded or unnecessary files, getting rid of temporary files, deleting no longer needed programs, and doing periodic preventive  maintenance on the hard drive.  Another hard drive can also be added to increase the storage capacity as well.  An important thing to remember, however, is that programs or other files should never be deleted until you are sure that they can be safely deleted, and that you have a backup of those files, just in case they need to be reinstalled later.  Always be sure to consult a professional computer technician or consultant if you are not sure how to safely perform any of these functions on a computer.

    There are a wide variety of other types of storage devices as well.  The "floppy drive" for instance, is very similar to the hard drive in your computer, except that it does not have near the storage capacity, but does allow you to store information onto "diskettes", and take your files with you, perhaps for using on other computers.  Nowadays, there are many new types of storage devices which have greater storage capacities, and also allow a great deal of portability.  Devices such as "Zip Drives" (see Figure 3, below), "Jaz Drives" (older types of storage), and newer types of CD-ROM and DVD drives allow the user to store extremely large amounts of data, and provide the portability to allow the user to take their data with them.  More recently, "thumb drives" or "flash drives" have become extremely popular because of their low cost and small size - making portable storage even more convenient.

 Figure 3:  Zip Drive, External Storage Component

Figure 4: Thumb Drive, aka Flash Drive, aka Jump Drive

So What's The Point?

    When you're trying to diagnose the operation of your computer, especially if you think you are having a problem and need help, it is best if you can explain to the technician exactly what the problem is.  That way, he or she will be able diagnose and repair your problem quickly, rather than having to decode your thoughts to find out the correct meaning of what you think might be wrong.  You will be able to speak about your computer much more intelligently, and others will know exactly what it is that you are trying to describe to them.  In this world of "high-tech", terminology... correct terminology is the key to success when communicating ideas or trying to describe a problem.  To put it in perspective, let me give you a true story:  Back when I was an avionics technician in the Navy, it was common for one of the pilots to walk in and say "... hey, my airplane doesn't work..."   No kidding?  Could you please narrow that down a little?  I was absolutely amazed by this statement because the airplane has hundreds of systems, and thousands of possibly failed components.  They would usually run off before we could get to the bottom of finding out the actual failed system.  My technicians and I would spend countless hours running thorough systems checks to find the problem.  Don't put your computer technicians through all that... tell them the problem succinctly, and with the correct terminology... and I promise, they will get you up and running much more quickly!

 

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