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Re: More Ports for Debian's

>OK, when two devices share the same IRQ and an that interrupt occurs,
>kernel doesn't have a clue which of the devices to service (that's
>what's special about multiport boards -- they contain extra 
>logic to handle this.)  So, you need an IRQ line per port. :(

This is actually what confuses me. First it seemed logical to me that
each device needed it's own IRQ. Then somebody told me that an
IRQ can be shared as long as the IO addresses are different. Now,
you (and the second person who answerd me) tell me that this is
not possible for OS's like NT or Linux, but Windows 95 say COM3
conflicts on IRQ4 with COM1, and COM4 on IRQ3 with COM2.
After disabeling COM4, Windows 95 thinks COM4 still exists with
the same conflicts (I let it `detect' new hardware), and Linux only
mentions three ports in the startup messages (no matter if COM4
is {en|dis}abeld). Then cua0..2 work, although in another order.

Finally, things are getting worse, as I just realized that I've no floppy;
this card brings another floppy interface and seems the shadow the
onboard one.

>Perhaps you could use DOS utility to configure your PnP stuff so that
>IRQ 3 & 4 are left for new ports, and then use loadlin.exe to start
>linux.  That's how I configure my PnP soundcard.

The thing closest to DOS I have installed is Windows 95. Which would
be an appropriate utility? The new card is not PnP. Which is the reason
for using loadlin instead of lilo?

>As for having a go with a hammer, layout diagram for ISA connector 
>will tell you which contact strips on the edge of the card carry IRQ
>channels (the diagram shouldn't be too difficult to find I'm sure.)  
>If you cut the tracks going to IRQ 3 & 4 contact strips -- you'll
>disable the ports.  Then you solder a wire connecting those tracks 
>to different contact strips, for different IRQ lines.  Of course you
>want IRQs that are not used by anything.

Where can I find such an assignment? Did I understand this right: Each
IRQ is associated with one of those golden contacts that slip into the slot,
and each track belonging to an IRQ which goes thru enables it? So if I cut the
track for IRQ4 (which seems to make troubles) and bridge it to another
track (e.g., 6) I'll have resolved the conflict, assuming there is nobody
using IRQ 6 yet?


Ciccio C. Simon

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