Adaptec RAID 2100S Software User's Manual page 27

Storage Manager on ROM
Select Default to reset the parameters on this tab to their default
values.
Mem Address, IRQ
The values in the Mem Address and IRQ fields may be needed when
you configure your operating system. These fields are read only.
PCI MWI Enable
Do not change this setting unless instructed to do so by Technical
Support.
Boot Enable
This option enables you to modify the system boot process for host
systems with multiple peripheral controllers in cases where the
controller BIOS does not provide effective or appropriate default
operation. This setting is enabled by default.
The host system uses the controller with the lowest BIOS address as
the booting controller. Therefore, in a system with multiple Adaptec
RAID controllers, you must ensure that the controller that you want
to use as the booting controller occupies the lowest BIOS address,
which usually corresponds with the lowest-numbered.
If you disable this setting, the controller can not be used as a boot
device.
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