Memory

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.

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.

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!

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%.