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Document ID: DETR-3UFPER |
Aptiva-PS/1 - What is expanded memory?
Applicable to: United States
Expanded memory (EMS) is typically extended memory (XMS) that has been converted using a memory management utility or memory installed using an expanded memory adapter card. Expanded memory, if converted, will reside in the same block of memory addresses above 1.0 MB that extended memory occupies. Not all systems can use expanded memory as readily as extended memory.
Systems based on the 286 processor cannot access expanded memory unless a special Expanded memory (EMS) hardware adapter card is installed into an expansion slot. (NOTE: This is not the front slot on early PS/1s that holds the 512KB or 2MB Memory Expansion Cards.) Since the early 286 PS/1s do not have expansion slots, installing a special EMS adapter card would require the PS/1 Adapter Card Unit which provides one 9.5" slot and two 11" slots.
Systems based on the 386, 486 and above processors can access system memory (extended) as expanded when using the DOS memory manager (EMM386.EXE) or another memory management software, such as QEMM, 386 MAX, Above Disk, etc.
Programs must be designed to use expanded memory. Otherwise, programs are generally designed to use extended memory. Specifying expanded memory with the EMM386 memory manager consumes 64K of upper memory for operational purposes. This can greatly hinder some TSR's and device drivers from loading high, into upper memory. Because of this, the amount of conventional memory free for programs is typically decreased. Therefore, verify that the program needs expanded memory before specifying it with the EMM386 memory manager.
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Hint Category |
Memory, DOS/Windows 3.x | |
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Date Created |
23-04-96 | |
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Last Updated |
02-04-99 | |
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Revision Date |
01-08-99 | |
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Brand |
IBM Aptiva | |
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Product Family |
Aptiva, PS/1 | |
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Machine Type |
2134, 2136, 2137, 2138, 2140, 2142, 2144, 2159, 2161, 2162, 2168, 2176, 2011, 2121, 2123, 2133, 2155 | |
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