From: Vinzent Hoefler <JeLlyFish DOT software AT gmx DOT net>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Libnet serial port problem
Date: Wed, 15 Jan 2003 09:58:14 -0500
Organization: JeLlyFish software
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To: djgpp AT delorie DOT com
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Reply-To: djgpp AT delorie DOT com

Tonu Aas wrote:

>> > If they use the same IRQ(COM1, COM3 or COM2 COM4) then its normal.
>>
>> No. Just bad software. There are enough status bits on the UART chip
>> to see which one has raised the interrupt. It just slows down a
>> little bite, because you have to ask all possible UART that are
>> sharing the same IRQ.
> 
> You expect that UARTS can share IRQ-s.

Yes, because I know it is possible.

> I dont know, but on older machines they dont.

They can. In theory, at least.

> At least ISA bus IO cards dont.

Sure they can, as long as all UARTs are on the same card.

> So its not "Just bad software" but can
> be also bad harware as most PC platform hardware is.

Yes, this might be the case.

> I think that this libnet is some older library and it doesnt handle
> IRQ sharing also.

As I said: Bad software. ;-)

> Only bullet-proof solution is to not use the same IRQ or not to use
> IRQ at all :[

I know.


Vinzent.

-- 
A student who changes the course of history is probably taking an
exam.