[WriteLog] WriteLog, shared IRQs and COM ports

[Larry L Lindblom]

I'm not a propeller head, but my understanding is the PCI Bus has IRQ
Steering which handles multiple devices on one IRQ.  I welcome correction
if I am wrong by a certified propeller head.

73 W0ETC


On Wed, 08 Jan 2003 22:53:09 +0000 K4SB <k4sb@earthlink.net> writes:
> Robert Peterson wrote:
> > 
> > Eric -  I want to echo Clive's comments....snip... handled it 
> without any problems.  > I'm assuming that systems that allow IRQ 
> sharing have some way of telling which device requested the 
> interrupt and activate the appropriate interrupt handler.
> 
> Well, as it was explained to me, Robert hit it right on the head. 
> The
> card sharing the IRQ (say IRQ 11) just sits there and polls how 
> many
> ports are present on the card. If it finds data coming in, it 
> assigns
> the IRQ to that port until business if transacted, and then goes 
> back
> to polling. It very well say, get a packet announcement, then get 
> an
> answer from the Radio in response to an earlier request.
> 
> However, only 1 port has the IRQ at a time. But then, at several
> hundred thousand polls per mili second, most of us can't keep it 
> with
> it.
> 
> Sounds like witchcraft to me.
> 
> 73
> Ed
> 
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