Specifications

Chapter 4: BIOS Configuration

Page 33

Memory Shadow Sub-Menu

The term “shadowing” refers to the technique of copying BIOS extensions from ROM

into DRAM and accessing them from DRAM. This allows the CPU to access the

BIOS extensions much more quickly and generally increases system performance if

many calls to the BIOS extensions are made. The Memory Shadow Sub-menu is

shown below.

The shadow regions should be used only if an EXMbus card is installed in the system

that contains a BIOS extension (ROM) although there is no effect on the system if a

region is shadowed that does not contain a BIOS extension. Note that each shadow

region in the setup menu is 16KB in size. Multiple shadow regions may have to be

enabled if the BIOS extension to be shadowed is larger than 16KB.

System Shadow/Video Shadow

These options are not editable since the System and VGA BIOS are always shadowed.

Shadow Memory Regions

These options enable or disable shadowing for the associated memory region. The

default is “Disabled”.

Item Specific Help

F1 Help Select Item -/+ Change Values F9 Setup Defaults

ESC Exit Select Menu Enter Select Sub-Menu F10 Previous Values

<Tab>, <Shift-Tab>, or

<Enter> selects field.

Memory Shadow

System Shadow: Enabled

Video Shadow: Enabled

Regions with Legacy Expansion ROMs:

C800-CBFF: [Disabled]

DC00-DFFF: [Disabled]

D800-DBFF: [Disabled]

CC00-CFFF: [Disabled]

D400-D7FF: [Disabled]

D000-D3FF: [Disabled]

Figure 4-4. Memory Shadow Menu.