Aaeon SBC-598 Manual page 49

Gate A20 Option
This entry allows you to select how gate A20 is handled. Gate A20
is a device used to address memory above 1 MB. Initially, gate A20
was handled via a pin on the keyboard. Today keyboards still
provide this support, however it is more common and much faster
for the system chipset to provide support for gate A20. The
choices are thus: Normal and Fast.
Security Option
This category allows you to limit access to the system. The
choices are System: which requires a password at boot up and
Setup: which only requires a password to access the setup utility.
Video BIOS Shadow
Determines whether the video display card BIOS will be copied
into system DRAM in order to increase display speed and is
required for system performance. However, it is optional
depending on the chipset design. The default setting is Enabled.
Shadowing Address Ranges
The next six lines, from C8000-CBFFF Shadow to CD000-
DFFFF Shadow are address ranges for shadowing other expansion
card ROMs. If there are any expansion cards with ROMs installed
in your system, you have to know the address range they use in
order to shadow them specifically. The default setting for all of
these is Disabled.
Chapter 3 Award BIOS Setup 41