User`s manual

4. BIOS SETUP
OS select for DRAM > 64MB
Select “OS2” only if you are running OS/2 operating system with greater than 64 MB
of RAM on your system.
Shadow
This is software that resides in a Read-Only Memory, (ROM), chip on a device is
called “firmware”. The Award BIOS permits “shadowing” of firmware such as the
system BIOS, video BIOS, and similar operating instructions that come with some
expansion peripherals, such as, for example, a SCSI adaptor.
Shadowing copies firmware from ROM into system RAM, where the CPU can read it
through the 16-bit or 32-bit DRAM bus. Firmware not shadowed must be read by the
system through the 8-bit X-bus. Shadowing improves the performance of the system
BIOS and similar ROM firmware for expansion peripherals, but it also reduces the
amount of high memory (640 KB to 1 MB) available for loading device drivers, etc.
“Enable” shadowing into each section of memory separately. Many system designers
hard-wire shadowing of the system BIOS and eliminate a System BIOS Shadow option.
Video BIOS shadows into memory area C0000-C7FFF. The remaining areas shown on
the BIOS Features Setup screen may be occupied by other expansion card firmware. If
an expansion peripheral in your system contains ROM-based firmware, you need to
know the address range the ROM occupies to shadow it into the correct area of RAM.