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Description
ESCD Pool Data in conjunction with PnP capable operating system (Windows 9x
/ 2000 / ...)
On machines with an ESCD the OS may insert references to non-PnP devices without
your knowledge ! This is, of course, to help the BIOS come up with a 'better'
working boot configuration (by helping the BIOS know about used resources that
the BIOS couldn't normally detect). This explains why (A) re-booting a non-working
Windows PC sometimes makes it work (and also why Windows wants to reboot all
the time when adding new hardware), and (B) also explains how those entries
got there in the first place.
Windows removes entries from the ESCD when you delete a device from Device Manager.
However it won't remove ESCD entries it doesn't have device manager entries
for. Thus, the ESCD can be left in a state where 'false' entries remain if a
non-PnP device is removed from the system and, say, Windows is deleted, re-installed,
etc at the same time without actually deleting the existing non-PnP device from
device manager first.
Some BIOS's have a "Reset Configuration data" CMOS setup option to erase the
ESCD and 'start over'. In this case, USE IT !
If the BIOS doesn't have such a function, you are in trouble.
Why does this happen?
It's a Catch 22 situation. Windows only alters the ESCD according to changes
made in Device Manger. The BIOS only updates PnP info in the ESCD, not non-PnP
info. Windows trusts the BIOS to have the ESCD info 'right' for devices it does
not have listed in it's device manager registry, and similarly the BIOS doesn't
delete any non-PnP entires other programs put there, as it is trusting that
those devices really do exist and need to be taken into account.
Each is trusting the other and nobody is doing the housekeeping. Remember, this
only applies to non-PnP devices - namely Legacy VESA & ISA devices - it can
never apply to PnP compatible devices.