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Revision as of 13:54, 22 September 2025 by DonteNeely601 (talk | contribs) (Created page with "[https://www.investopedia.com/terms/o/operating_expense.asp investopedia.com] <br>In DOS memory management, expanded memory is a system of bank switching that offered additional memory to DOS programs past the restrict of typical memory (640 KiB). Expanded memory is an umbrella term for a number of incompatible expertise variants. The most widely used variant was the Expanded Memory Specification (EMS), which was developed jointly by Lotus Software, Intel, and Microsoft,...")
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In DOS memory management, expanded memory is a system of bank switching that offered additional memory to DOS programs past the restrict of typical memory (640 KiB). Expanded memory is an umbrella term for a number of incompatible expertise variants. The most widely used variant was the Expanded Memory Specification (EMS), which was developed jointly by Lotus Software, Intel, and Microsoft, so that this specification was sometimes referred to as "LIM EMS". LIM EMS had three variations: 3.0, 3.2, and 4.0. The primary extensively applied version was EMS 3.2, which supported up to 8 MiB of expanded memory and makes use of components of the deal with area usually dedicated to communication with peripherals (upper memory) to map portions of the expanded memory. EEMS, an expanded-memory management customary competing with LIM EMS 3.x, was developed by AST Analysis, Quadram and Ashton-Tate ("AQA"); it could map any area of the decrease 1 MiB. EEMS ultimately was integrated in LIM EMS 4.0, which supported up to 32 MiB of expanded Memory Wave System and supplied some help for DOS multitasking as properly.



IBM, nevertheless, created its own expanded-memory normal referred to as XMA. The use of expanded memory turned widespread with games and business packages reminiscent of Lotus 1-2-three within the late 1980s by means of the mid-1990s, however its use declined as customers switched from DOS to protected-mode working techniques such as Linux, IBM OS/2, and Microsoft Home windows. The 8088 processor of the IBM Laptop and IBM Pc/XT can deal with one megabyte (MiB, or 220 bytes) of memory. It inherited this restrict from the 20-bit exterior address bus (and total memory addressing architecture) of the Intel 8086. The designers of the Laptop allocated the lower 640 KiB (655360 bytes) of tackle house for read-write program memory (RAM), called typical memory, and the remaining 384 KiB of memory space is reserved for uses such because the system BIOS, video memory, and memory on expansion peripheral boards. Even though the IBM Laptop AT, introduced in 1984, uses the 80286 chip that may address up to sixteen MiB of RAM as extended memory, it may only achieve this in protected mode.



The scarcity of software program compatible with protected mode (no normal DOS functions can run in it) meant that the market was nonetheless open for Memory Wave one more resolution. To make more memory accessible, a bank switching scheme was devised, the place only chosen elements of the extra memory is accessible at any given time. Originally, a single 64 KiB (216 bytes) window of memory, known as a web page body, was used; later this was made more versatile. Packages are written in a particular technique to access expanded memory. The window between conventional memory and expanded memory could be adjusted to access totally different areas throughout the expanded memory. The primary publicly out there version of EMS, model 3.0 permits entry of as much as four MiB of expanded memory. This was elevated to eight MiB with version 3.2 of the specification. The ultimate model of EMS, version 4.0 increased the maximum quantity of expanded memory to 32 MiB and supports additional functionality.



Microsoft thought that bank switching was an inelegant and temporary, but necessary stopgap measure. Slamming his fist on the table throughout an interview Bill Gates stated of expanded memory, "It's rubbish! It is a kludge! … But we'll do it". The companies deliberate to launch the standard at the Spring 1985 COMDEX, with many expansion-card and software companies saying their help. AST Analysis, STB Systems, Memory Wave Persyst, Quadram, and Tecmar shortly designed EMS-compliant playing cards to compete with Intel's personal Above Board enlargement card. By mid-1985 some already referred to as EMS a de facto customary. The first public model of the EMS normal, referred to as EMS 3.Zero was released in 1985; EMS 3.0, nevertheless, saw almost no hardware implementations before being superseded by EMS 3.2. EMS 3.2 uses a 64 KiB region in the upper 384 KiB (higher memory space) divided into four 16 KiB pages, which can be used to map portions of the expanded memory. Quadram, AST, and Ashton-Tate created the Enhanced EMS (EEMS) normal.