Date: Fri, 19 Jul 96 14:30:00 PST From: "Brett Glass" <Brett_Glass@ccgate.infoworld.com> To: <E00114@vnet.atea.be> (Rob Schofield), freebsd-hardware@freebsd.org Subject: Re: Multiple COM ports with same IRQ Message-ID: <9606198378.AA837808823@ccgate.infoworld.com>
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It'd only be possible to implement shared IRQs on ISA if
(a) The motherboard chipset can accept level-triggered interrupts;
(b) Each peripheral board sharing the IRQ was rewired to be
open-collector (many are implemented in VLSI, so you'd probably
have to cut traces and add parts);
(c) A pullup resistor was placed on the motherboard; and
(d) All the software (including, possibly, the BIOS) was rewritten
to work with the changed hardware.
Whadda mess.
--Brett
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