Adastra Systems NPC-486E, Руководство пользователя

Страница: 18 / 105

11
3.2 Changing Memory Configuration
If physical memory is removed or added to the system, BIOS will detect the changes
during the power-on self-test period (POST) after reset. It will report the change and
request that Set-up be run.
Run the BIOS Set-up to configure the memory so that BIOS will correctly account for the
memory change. Running Set-up will eliminate the power-up warning.
3.3 Logical Configurations
Portions of the system memory may be allocated as conventional memory, extended
memory, expanded memory, or shadow memory. Conventional, extended, and expanded
memory are all accessible to programs for their own use. Shadow memory is used
exclusively by BIOS. The mix of conventional, extended, expanded, and shadow memory
is dictated primarily by the operating system and programs which will run on the NPC-
486E.
3.2.1 Conventional Memory
Conventional memory is the first 640K bytes of RAM. This memory block is used
extensively by various operating systems and programs common on the PC/AT.
3.2.2 Expanded Memory
Expanded memory refers to a design which allows access to a large address space (e.g.
32M bytes) on a processor such as the 8088, that has address lines to directly address only
1M byte of memory. 16K or 64K sections of memory, called pages, can be "switched"
into addressable blocks (holes) in the expanded memory range. Programs must use the
BIOS extension known as LIM (Lotus/Intel/Microsoft) Expanded Memory Services to
control the switching of pages.
3.2.3 Extended Memory
This is memory beyond the first 1 MB. This memory is directly addressable by programs
in the NPC-486E. However, it is usually controlled by an installed memory manager, such
as HIMEM.SYS, to prevent programs from using the same area of extended memory.