XMS
Remainder of all Memory above 1MB except the first
640KB |
| External memory (XMS) - directly accessible memory starting at 1 MB requires HIMEM.SYS
as an external memory manager (loaded in config.sys) 80386 Limited to
16 MB 80286 Limited to 8 MB
XMS
Definition
|
HMA
First 64KB of memory Beyond 1MB |
| High memory area (HMA) - first 64 KB of XMS also requires HIMEM.SYS as an external
memory manager (loaded in config.sys) Only 1 program at a time can
access HMA Commonly used for loading DOS "high", but
also used for TSRs.
HMA
Definition
|
UMB
384KB |
| Upper memory area (UMA) is located between 640KB and 1MB.
Contains the ROM BIOS, device controller ROM, and video controller ROM and RAM
UMB
Definition
|
CONVENTIONAL
640KB
(This is static and will never change no matter how much ram you have in the computer. |
| Conventional memory - traditionally was the only memory available to DOS It contains devices drivers, conventional variables, the DOS
command Processor, TSRs application programs, an data.
Conventional
Memory definition
|
