[rescue] AT&T 3b1 Starlan software

[Scott Newell]

>Why would a card need more than one interrupt line?  The card itself

I guess it wouldn't.  One drawback would be with something that integrates
multiple devices onto a single card: imagine a super I/O expander, with
floppy, 2 serial, parallel, game port, and IDE hard drives.  Not something
the Apple II guys had to worry about at that time, however.


>should only need one line to the CPU to say "Hey!  I have data!".  The
>notion of needing, for example, one IRQ per serial port is wasteful.
>It's not hard at all to multiplex interrupts for a multiport card.  The
>CPU can only service one interrupt at a time, so you really don't gain
>anything by having the serparate IRQs.

I dunno...I kinda like the idea of one interrupt per peripheral/function.
Multiple serial ports sharing IRQ...ok.  Multiple ethernet interfaces?  How
'bout one IRQ for the entire CPU--kindy 'risc'y, huh?  That's a different
argument, though.  ;-)


newell