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WHAT IS MEMORY?
INTRODUCTION
These days, no matter how much memory your computer has, it never seems to be
quite enough. Not long ago, it was unheard of for a PC (Personal Computer), to
have more than 1 or 2 MB (Megabytes) of memory. Today, most systems require
64MB to run basic applications. And up to 256MB or more is needed for optimal
performance when using graphical and multimedia programs.
As an indication of how much things have changed over the past two decades,
consider this: in 1981, referring to computer memory, Bill Gates said, "640K
(roughly 1/2 of a megabyte) ought to be enough for anybody."
For some, the memory equation is simple: more is good; less is bad. However, for
those who want to know more, this reference guide contains answers to the most
common questions, plus much, much more.
THE ROLE OF MEMORY IN THE COMPUTER
People in the computer industry commonly use the term "memory" to refer to RAM (Random
Access Memory). A computer uses Ram to hold temporary instructions and data needed
to complete tasks. This enables the computer's CPU (Central Processing Unit), to
access instructions and data stored in memory very quickly.
A good example of this is when the CPU loads an application program - such as a word
processing or page layout program - into memory, thereby allowing the application
program to work as quickly and efficiently as possible. In practical terms, having
the program loaded into memory means that you can get work done more quickly with less
time spent waiting for the computer to perform tasks.
The process begins when you enter a command from your keyboard. The CPU interprets
the command and instructs the hard drive to load the command or prgram into memory.
Once the data is loaded into memory, the CPU is able to access it much more quickly
than if it had to retrieve it from the hard drive.
This process of putting things the CPU needs in a place where it can get at them more
quickly is similar to placing various electronic files and documents you're using on
the computer into a single file folder or directory. By doing so, you keep all the
files you need handy and avoid searching in several places every time you need them.
THE DIFFERENCE BETWEEN MEMORY AND STORAGE
People often confuse the terms memory and storage, especially when describing the
amount they have of each. The term memory refers to the amount of RAM installed
in the computer, whereas the term storage refers to the capacity of the computer's
hard disk. To clarify this common mix-up, it helps to compare your computer to
an office that contains a desk and a file cabinet.
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The file cabinet represents the computer's hard disk, which provides storage for
all the files and information you need in your office. When you come in to
work, you take out the files you need from storage and put them on your desk for
easy access while you work on them. The desk is like memory in the computer: it
holds the information and data you need to have handy while you're working.
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Consider the desk-and-file-cabinet metaphor for a moment. Imagine what it would
be like if every time you wanted to look at a document or folder you had to retrieve
it from the file drawer. It would slow you down tremendously, not to mention drive
you crazy. With adequate desk space - our metaphor for memory - you can lay out
the documents in use and retrieve information from them immediately, often with
just a glance.
Here's another important difference between memory and storage: the information
stored on a hard disk remains intact even when the computer is turned off.
However, any data held in memory is lost when the computer is turned off. In our
desk space metaphor, it's as though any files left on the desk at closing time will be
thrown away.
MEMORY AND PERFORMANCE
It's been proven that adding more memory to a computer system increases its
performance. If there isn't enough room in memory for all the information the CPU
needs, the computer has to set up what's known as a virtual memory file. In so
doing, the CPU reserves space on the hard disk to simulate additional RAM. This
process, referred to as "swapping", slows the system down. In an average computer,
it takes the CPU approximately 200ns (nanoseconds) to access RAM compared to
12,000,000ns to access the hard drive. To put this into perspective, this is equivalent
to what's normally a 3 1/2 minute task taking 4 1/2 months to complete!
Access time comparision between RAM and a hard drive.
MEMORY UPGRADE ON A PC: LIFE IS GOOD
If you've ever had more memory added to your PC, you probably noticed a
performance improvement right away. With a memory upgrade, applications
respond more quickly, Web pages load faster, and you can have more programs
running simultaneously. In short, additional memory can make using your
computer a lot more enjoyable.
MEMORY UPGRADE ON A SERVER: LIFE IS EVEN BETTER
These days, more and more people are using computers in a workgroup and sharing
information over a network. The computers that help distribute information to
people on a network are called servers. And their performance has a huge impact
on the performance of the network: if a server is performing poorly, everyone on
the network "feels the pain." So, while a memory upgrade on an individual PC
makes a big difference for the person who uses it, a memory upgrade in a server
has even more far-reaching effects and benefits everyone who accesses the server.
To better understand the benefits of increasing memory on a server, take a look at
these results from an independent study done on Windows
NT-based servers.
Application servers are utilized to host a wide range of applications, such as word
processing and spreadsheet programs. By increasing base memory from 64MB to 256MB,
Windows NT Server was able to support five times as many clients before transactions
per second dropped.
Web servers are employed to serve up Web pages in response to HTTP requests from
users. Doubling memory can cut response time by more than 50%.
Directory servers are vital to corporate productivity, handling most email and
messaging tasks. In this environment, more memory increases the speed with which
a server can access information from linked databases. Doubling memory increased
performance from 248 to 3000%.
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