Setting System Parameters 4-19
Base Memory Size
The Base Memory Size field controls the mapping of
addresses between “512 KB” and “640 KB.” The two
choices are described as follows.
512 KB
−
directs address mapping between 512 KB and
640 KB to the ISA bus.
640 KB (default)
−
directs address mapping between
512 KB and 640 KB to the system DRAM. Unless using
an ISA expansion board that requires access to this
address range, this field should not be changed.
ISA LFB Size
The ISA Video Linear Frame Buffer (LFB) Size provides a
mechanism for creating a hole in the system memory map.
Address accesses made to this hole will be directed to the
ISA bus instead of main memory.
This “Disabled” setting should not be changed unless you
are using an ISA board which has memory greater than
64K, needs to be accessed by the CPU, and you are not
using the Plug and Play run-time utilities. The following
choices are available.
Disabled (default)
1 MB
2 MB
4 MB
ISA LFB Base Address
This field cannot be entered, it is an information field only.
If the ISA LFB field is “Disabled,” this field does not
appear.
The ISA Video LFB Base Address field displays “15 MB”
(the starting address of the ISA memory hole) if “1 MB” is
chosen as the ISA LFB Size parameter.
