Legacy Devices and Reserving Resources Question

I've managed to get myself confused about when it is, and isn't necessary to
reserve the resources a legacy device needs.

For example, lets say I'm installing an ISA network card. I've done my
research, and the card will need IRQ 5. I'm ignoring the other possible
resource needs to keep the example simple. Device Manager shows me that IRQ5
is being used by some random PnP device. To my understanding, here I would
have to reserve IRQ5 in Device Manager | Computer Properties | Reserve
Resources , then shut down, physically install the card and reset the ESCD
in CMOS upon booting.

My question then, is what if when I checked out Device Manager, there was no
device using IRQ5? Would I still need to reserve the IRQ to stop something
other than my legacy device getting shuffled in there when the ESCD was
reset? I seem to remember that PnP allocates legacy resources first, and
then PNP but the book doesn't seem clear to me on this.
Also, if it is necessary to reserve that resource to ESCD shuffle proof it
(tm), then would I have to reserve ALL the resources (I/O, DMA etc) the
legacy device would use just to be safe?

Hope that's not too convoluted. Look forward to someone who has more of a
clue than I setting me straight.

Bloke_in_a_box

Thanks for the clarification Will Sometimes I doubt the description of
this certification as entry level when I just can't get my head around
something.
"Will Dormann" <> wrote in message
news:_iOlc.63940$...
> Bloke_in_a_box wrote:
>
> > My question then, is what if when I checked out Device Manager, there
was no
> > device using IRQ5? Would I still need to reserve the IRQ to stop
something
> > other than my legacy device getting shuffled in there when the ESCD was
> > reset?
>
> Yes.
>
>
> > Also, if it is necessary to reserve that resource to ESCD shuffle proof
it
> > (tm), then would I have to reserve ALL the resources (I/O, DMA etc) the
> > legacy device would use just to be safe?
>
> Yes, you will want to set the DMA as being used by a Legacy device, too.
> (assuming the BIOS supports it). I/O resources generally do not
> overlap, so that's not a BIOS option you need to worry about. (Nor am
> I aware of any BIOS that lets you specify that)
>
>
> -WD

Bloke_in_a_box