Re: Question: Multiple Super Serial Card ][s in //e?

["Mark Cummings" <NOTfigjams@primus.com.au>]

What annoys me the most on the PC is that manufacturers of cards only
normally allocate a choice of a few IRQ's for a particular card(s). I have
tried to free up some unused IRQ's so that other cards could use them, but
keep running into the problem that the other cards don't have that IRQ as a
choice. For example try to free up IRQ6 if you remove your floppy drive or
IRQ15 if you're only using 1 IDE port, and you'll be lucky if you can use
that IRQ for another card as it's not a hardware option.

Mark


>But it is getting better. The problem was with the original ISA bus. It
uses
>edge triggered active high going IRQ lines. These cannot be shared by two
>or more cards. The PCI bus uses level sensitive active low lines just like
>the IRQ line on the Apple II and provided the drivers are correctly written
>any number of cards can share the same IRQ line.
>--
>David Wilson  School of IT & CS, Uni of Wollongong, Australia