| A | B |
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| The operating system that runs the computer uses physical memory (RAM), also known as | system memory, and virtual memory. |
| The four categories of system memory in the operating system include | conventional, upper/expanded, high, and extended memory |
| The logical divisions or categories of memory are the result of MS-DOS and | early microprocessors, all associated with the early IBM PC, having been designed to address only a maximum of 1 MB of memory space. |
| The first 640KB of the 1 MB of memory space was used for | user and OS |
| The the upper 384KB of the 1 MB of memory space was used for | BIOS and utilities. |
| Because Windows 9x, supports the different types of physical memory specifications because it | is basically built on an MS-DOS foundation, |
| Conventional memory includes all memory addresses between | 0 and 640KB |
| Conventional memory | base memory |
| Conventional memory is the | area where MS-DOS programs normally run |
| Memory-resident routines include Terminate-and-Stay-Resident (TSR) Programs such as | mouse and CD-ROM drivers. |
| Upper memory includes memory addresses that fall between | 640KB and 1024KB (1MB) |
| Reserved Memory | Upper memory |
| Upper memory is available in the form of | Upper Memory Blocks (UMBs). |
| Programs that run in Upper memory include | system BIOS, plug and play BIOS, video BIOS and video RAM |
| If an appropriate memory manager such as Emm386.EXE is installed during the startup process, between 96KB and 160KB of upper memory space is | not in use by hardware |
| This program frees up conventional memory by allowing unused portions of the reserved memory area to be used for DOS drivers and memory resident routines | Emm386.EXE |
| Expanded Memory (also called the Expanded Memory Specification (EMS)) | can be accessed in pages (16KB chunks) from a 64KB page frame, established in unused Upper Memory Blocks (UMBs) |
| With the advent of the 80286 microprocessor and its protected operating mode, it became possible to | access physical memory locations beyond the 1 MB limit of the 8088/8086 |
| Memory above the 1MB address is generally referred to as | Extended Memory |
| 1MB | 1024KB |
| Extended Memory or Extended Memory Specification (XMS) is the primary memory area used by | Windows 9x. |
| A device driver, loaded by the OS that controls Extended Memory | Himem.sys |
| the first 64KB of extended memory is called the | High Memory Area (HMA) |
| the MS-DOS kernel used by Windows 9x | runs in High Memory Area (HMA) |
| Extended Memory Area | controlled by HIMEM.SYS |
| Upper Memory Area | Controlled by EMM386.EXE |
| Memory manager emulates expanded memory and makes upper memory available for use by the OS. | EMM386.EXE |
| To add MS-DOS applications needing access to EMS memory, include the statement | Device=C: \Windows\Emm386.exe RAM in the Config.sys file. |
| To add MS-DOS TSR utilities into upper memory blocks, include the line | Device=C: \Windows\Emm386.exe NOEMS in the Config.sys file. |
| To load HIMEM.SYS , include the line | DEVICE=C:\DOS\HIMEM.SYS in the Config.sys file. |
| This option is added into Config.sys file to tell the OS to move a portion of itself (such as MS-DOS Kernel) into the high memory area. | DOS=HIGH |
| put upper memory blocks to use, once HIMEM.SYS and Emm386.exe have been loaded. | DEVICEHIGH (used in Config.sys) and LOADHIGH (used in Autoexec.bat) |
| This utility will automatically insert the needed entries in the Config.sys and Autoexec.bat files. | MemMaker |
