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                                     4
                                



                                    RAM 
                                 






















Help Guide to Buying a Computer





Chapter 4 - RAM


     Random Access Memory (also called RAM) is what the computer uses to
remember things it is working on at any one moment in time.  For example:  Let's
say you think of two numbers and you add those two numbers in your head.  You
haven't forgotten the original two numbers, and now you have a third number (the
two numbers added together) in your head. This is similar to how computer memory
(RAM) works.  RAM is referred to in a number of "Megabytes" so you'll hear or
see it written as some number of megabytes of memory (or RAM).  However,
sometimes manufacturers abbreviate the word "Megabytes" to MG, MB or Meg.

     Most people don't consider RAM an important part of buying a computer. 
This is probably due to the fact that they don't understand what a huge 
difference the amount of RAM the computer has can make on performance.  When 
purchasing a new computer, try to think ahead (remember Chapter 1) and determine 
your current and future needs.  Buy the amount of RAM you will need in the 
future (about 1 year) and not what you need today.  Why?  Simple...  the general 
rule of thumb regarding RAM is "you can never have too much".  However, it is 
very easy to have too little.

     Having the right amount of RAM (or more) greatly improves your computer's
performance when running large programs (DOS or Windows based).  For example: 
Windows performance can be increased by 25 percent or more by simply having
the right amount of RAM.  Only having 4 megabytes, however, is not considered
enough these days because most programs need more RAM.  The ideal amount of
RAM to buy is 12 megabytes simply because most programs need that much RAM
to run at acceptable speeds.  Having 8 megabytes will work for most computers, 
but having 12 megabytes will provide a 10%-20% increase in speed (especially 
when using Microsoft Windows or Windows 95 - see Chapter 11 for more 
information).  If you will be running multiple programs (at once) then 16 
megabytes makes more sense.  

     If you buy a laptop or notebook computer, intend to run it from the 
internal battery, and run large programs then you should consider buying it with 
even more RAM than you would buy for a comparable desktop computer.  The 
reasoning is simple; larger programs (especially Microsoft Windows based 
programs) access the internal hard disk drive (for more information see Chapter 
5) more often and will 














Help Guide to Buying a Computer





Chapter 4 - RAM


cause the battery to run down faster.  If your laptop or notebook computer has 
more RAM, then more of the program can be loaded into RAM at once, therefore, 
eliminating the need to access the hard disk drive as often and extending 
battery life.


Memory Types
------------

     RAM chips used to be sold as individual chips, but today several RAM chips
are soldered together onto a plug-in board called a module.  This RAM module is
called a SIMM (Single In-line Memory Module).   SIMMs come in two basic
designs: an older design that has 30 connector pins and a newer design that has 
72 connector pins.  Each computer is designed to use one or the other of these 
SIMM designs. When looking at new computers, only buy a computer that uses the 
newer 72 pin SIMM design.  It is less expensive and still superior in design to 
the 30 pin SIMM design so you'll get better SIMMs and pay less for them.

     SIMMs come in several difference speeds.  The most common speed is called
70 nanoseconds (ns).  The rule in RAM is the lower (or smaller) the nanosecond
number, the faster the RAM will operate.  Therefore, a 60 ns SIMM is faster than 
a 70 ns SIMM.  Don't buy a computer that has SIMMs slower than 70 ns (greater
than 70 ns such as 80 ns), because they'll be too slow to work with today's fast
CPUs (for more information see Chapter 3).  Some manufacturers are even 
including 60 ns SIMMs at no extra charge.  This is a bonus for you because your 
SIMMs will likely work with the next generation of CPUs.
























Help Guide to Buying a Computer



