B I O S a n d s e t u p
LS700 HANDBOOK 5/23
ISA Shared Memory Size
Enables you to specify a range of memory addresses that will
be directed to the ISA bus rather than to onboard memory.
The options are:
♦
Disabled (default)
♦
16 KB
♦
32 KB
♦
48 KB
♦
64 KB
♦
80 KB
♦
96 KB
If this field is set to Disabled, the ISA Shared Memory Base
Address field (described below) will not appear.
This field should be enabled only when you are using a non-
Plug and Play ISA add-in card (legacy card) that requires
non-ROM memory space. For example, video capture cards
that have video buffer memory.
By default, allocation of upper memory is as follows:
memory from C0000h-C7FFFh is automatically shadowed.
(This memory range is typically reserved for video BIOS.)
Memory from C8000h-DFFFFh is initially unshadowed.
The BIOS scans this range for any ISA add-in cards that
may be present and notes their location and size.
The BIOS will then automatically configure the PCI and
Plug and Play devices, shadowing the ROM requirements
(other than video) into the area above E0000h until that area
is full. It will then assign additional PCI and Plug and Play
add-in cards to the area between C8000h and DFFFFh. If
an ISA legacy card has non-ROM memory requirements, the
autoconfigure routine may write into an area that is needed
by the ISA add-in card.
