Webopedia on Google+Webopedia on TwitterWebopedia on FacebookTech Bytes Blog
Main » TERM » E »

expanded memory

Also known as EMS (Expanded Memory Specification), expanded memory is a technique for utilizing more than 1MB of main memory in DOS -based computers. The limit of 1MB is built into the DOS operating system. The upper 384K is reserved for special purposes, leaving just 640K of conventional memory for programs.

There are several versions of EMS. The original versions, called EMS 3.0 and 3.2, enable programs to use an additional 8MB of memory, but for data only. An improved version developed by AST, Quadram and Ashton-Tate is known as EEMS (Extended EMS). EEMS enables programs to use extra memory for code as well as for data. The most recent version of EMS (created in 1987) is known as EMS 4.0 or LIM 4.0, LIM being the initials of the three companies that developed the specification: Lotus, Intel, and Microsoft. EMS 4.0 raises the available amount of memory to 32MB.

Until the release of Microsoft Windows 3.0 in 1990, expanded memory was the preferred way to add memory to a PC. The alternative method, called extended memory, was less flexible and could be used only by special programs such as RAM disks. Windows 3.0 and all later versions of Windows, however, contain an extended memory manager that enables programs to use extended memory without interfering with one another. In addition, Windows can simulate expanded memory for those programs that need it (by using the EMM386.EXE driver).







TECH RESOURCES FROM OUR PARTNERS
DID YOU KNOW?
Keeping Data Secure Is Tougher than Ever

If hackers get their hands on your company's data, they can wreak havoc on customer relationships and cause tremendous damage to your brand and... Read More »

Windows XP: Move Along, There's Nothing to See Here

After more than 12 years of holding the title of most popular operating system in the world, Windows XP is taking center stage for its final... Read More »

Report: The Role of Big Data in the Marketing Industry

According to a new study from Infogroup Targeting Solutions, we can expect to see companies spend heavily on big data marketing initiatives in... Read More »

QUICK REFERENCE
How to Create a Desktop Shortcut to a Website

Creating desktop shortcuts to a websites is useful. When you double-click the icon from your desktop it automatically launches the browser and... Read More »

Flash Data Storage Vendor Trends

Although it is almost impossible to keep up with the pace of ongoing product releases, here are three recent highlights in the flash data storage... Read More »

15 Important Big Data Facts for IT Professionals

Keeping track of big data trends, research and statistics gives IT professionals  a solid foundation to plan big data projects. Here are 15... Read More »