Kingston Technology Corporation

The Ultimate Memory Guide

The Introduction

Introduction

These days no matter how much memory your computer has it never seems quite enough. Not long ago, it was unheard of for a personal computer, or PC, to have more than 1 or 2 megabytes of memory. Today, you need at least 4 megabytes of memory just to boot up a system; using more than one application at a time requires at least 8 megabytes, and maximum performance today calls for 16 megabytes or more.

To get an idea of how much things have changed over the last decade, an excerpt from Inside the IBM PC, written by Peter Norton in 1983, describes the merits of IBM's new XT computer:

"So IBM has equipped all XTs with what it considers to be the
minimum gear for a serious personal computer. Now the 10-megabyte
disk and the 128K [one eighth of a megabyte] of memory are naturals
for a serious machine."

For some, the memory equation is simple: more is good; less is bad.

However, for those who want to know more, this reference guide provides a general overview of what memory is and how it works.

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What is memory?

People in the computer industry commonly use the term memory to refer to Random Access Memory, or RAM. A computer uses random access memory to hold temporary instructions and data needed to complete tasks. This enables the computer's Central Processing Unit, or CPU, 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 processor or page layout program -- into memory, thereby allowing the application program to run as quickly as possible. In practical terms, this means you can get more work done with less time spent waiting for the computer to perform tasks.

When you enter a command from the keyboard, it calls for data to
be copied from a storage device (such as a hard disk drive or
CD-ROM drive) into memory, which can provide data to the CPU more
quickly than storage devices.

This "putting things the CPU needs in a place where it can get at them more quickly" process 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 them handy and avoid searching in several places every time you need those documents.

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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 available amount of hard disk capacity.

To clarify this common mix-up, it helps to compare your computer to an office that contains a work table and a set of file cabinets.

The file cabinets represent the computer's hard disk, which provides high-capacity storage.

The work table represents memory, which offers quick and easy access to the files you're working on at the moment.

Another important difference between memory and storage is that the information stored on a hard disk remains intact even when the computer is turned off. However, any data held in memory is cleared when the computer is turned off. (It's like saying that any files left on the work table at closing time will be thrown away.)

It's important to save frequently while working on a computer. The computer memory holds any changes you make to a document until you save the changes to a disk. If anything interrupts the computer's operation -- such as a power outage or system error -- any changes made, but not saved, are lost.

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How much memory is enough?

The right amount of memory varies according to the type of work you do and the type of software applications you're using. Today's word processing and spreadsheet work requires as little as 4 megabytes. However, systems equipped with 8 megabytes have become the low-end assumption by software and operating system developers. Systems used for graphic arts, publishing, and multimedia call for at least 16 megabytes of memory and it's common for such systems to have 32 megabytes or more.

Perhaps you already know what it's like to work on a system that doesn't have quite enough memory. Things run a little more slowly at times, memory errors can occur more frequently, and sometimes you can't launch an application or a file without first closing or quitting another. On a system with sufficient memory, however, you can do multiple tasks at once -- such as printing one document while working on another -- and you can keep multiple applications open simultaneously.

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Memory recommendation chart


Type of User/Usage                                           Recommended RAM
------------------------------------------------------------------------------

Light Administrative
Light word-processing, light e-mail                              8MB - 12MB

Medium Administrative      
Word-processing, E-mail, Fax & Comm. Software, Database. 
1-2 applications open at a time.                                12MB - 16MB

Heavy Administrative       
Word-processing, E-mail, Fax & Comm. Software, Spreadsheet, 
Business graphics. > 3 applications open at a time.             16MB - 24MB
                           
Light Customer Service     
E-mail, Database. 1-2 applications open at a time.               8MB - 12MB

Heavy Customer Service     
E-mail, Database, Fax & Comm. Software, Word processing.  
> 3 applications open at a time.                                12MB - 20MB
                           
Light Number Crunching     
Spreadsheet, E-mail, Accounting software
1-2 applications open at a time.                                16MB - 24MB
                           
Heavy Number Crunching
Spreadsheets, Statistical applications, Research, large 
databases. > 3 applications open at a time.                     24MB - 32MB

Light Graphics             
Word-processing, Page layout software, Illustration/graphics 
software. 1-2 applications open at a time.                      32MB - 64MB

Heavy Graphics             
Word-processing, Page layout software, Illustration/graphics 
software, Photo editing, Presentation software, Font packages, 
multimedia. > 3 applications open at a time.                    64MB - 128MB
                           
Executive/ Management
Word-processing, E-mail, Fax & Comm. Software, Spreadsheets, 
Business graphics programs, Database, Presentation software.
> 3 applications open at a time.                                16MB - 32MB 

Light - Medium Design      
CAD software, CAM software                                      32MB - 128MB

Heavy Design               
3D CAD software, CAM software solid modeling                    256MB - 2GB

Note:
Naturally, a chart such as this evolves as memory needs and trends change. While we can speculate today about the `right' amount of memory given systems or tasks, one thing appears certain: over time, developers of software and operating systems will continue to add features and functionality to their products. This will continue to drive the demand for more memory.

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What memory looks like

The Integrated Circuits, or ICs, that make up your computer's memory configuration are referred to as Dynamic Random Access Memory, or DRAM. DRAM is by far the most common type of memory chip. The quality of DRAM chips used in a memory module is the most important component in determining the overall quality and reliability of the module.

How DRAM fits on a SIMM

A common memory product is the Single In-line Memory Module, or SIMM. As you can see from the illustration, a typical SIMM consists of a number of DRAM chips on a small Printed Circuit Board, or PCB, which fits into a SIMM socket on a computer's system board (more on this later).

SIMMs come in a variety of forms, including 30- and 72-pin formats. These and other types of memory products are covered in greater detail in the `Bits and Bytes' section coming up later...

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