Memory Extenders

Many DOS applications use memory extenders, such as EMS and XMS, to gain access to memory above the 1MB real mode addressing limit of the 80286 and higher microprocessors. Such extenders allow DOS applications to have total code and data spaces larger than the available base memory, and to have very large code or data objects loaded into memory for improved speed. The standard configuration of OS/2 2.0 provides both LIM EMS Version 4.0 and LIMA XMS Version 2.0 functions for DOS applications running in DOS sessions. It also supports DPMI.

Users can choose to have DOS load video drivers and other device drivers into memory between 640KB and 1MB; it loads applications and data in the area below 640KB. DOS extenders take control to manage upper memory.



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