Subject: Re: NuBus cards conflict (Re: Daystar Accelerators)
To: Kazuyuki Inanaga <happyday@pp.iij4u.or.jp>
From: Allen Briggs <briggs@wasabisystems.com>
List: port-mac68k
Date: 01/21/2004 10:18:50
On Thu, Jan 22, 2004 at 12:08:28AM +0900, Kazuyuki Inanaga wrote:
> Thanks a lot.
> I'm reading hardly with a dictionary, I regret my poor english and
> less understanding of NetBSD. The conception "interrupt" is difficult
> to understand for me. My English-Japanese dictionary shows a strange
> translation for "interrupt", and it makes me confused much ;)

Ah.  I see.  I apologize that I can not write more clearly for you, and
that I only have a few words of Japanese, myself.

When we talk about computers and operating systems, an "interrupt"
means an electrical signal is sent to the CPU to tell it that it
needs to stop doing what it is doing and that it needs to do
something else.  If you have children, this situation might be
very clear.  My children "interrupt" me all of the time to make
me do something other than what I was doing.

I hope that helps, but please tell me if it does not.

> TAMA's IIci has Rudius GS/C and 2 Asante MacCon Ethernet, right?
> Why do they make a conflict?

In the Macintosh, all Nubus cards share one interrupt wire to the
system.  So if one nubus card would like to interrupt the CPU, we
don't know which one it is.  If we do not clear the cause of the
interrupt, it will just keep interrupting--causing the system to
appear to freeze (while it goes in circles).  Or the interrupt
will be missed and never handled.

The two Asante Ethernet cards should work fine by themselves, but
we probably do not support the Radius GS/C yet.  So when an interrupt
happens, we try to handle it by checking the ethernet cards.  If
the interrupt came from the Radius card, though, we will not handle
it and the system will get stuck in a loop--or the interrupt will
be missed and the ethernet interrupts will never be handled.

> I have a simple question. If I send Video Interrupt Information, it makes
> less conflict? If all member send own card Interrupt Informations,
> no more interrupt problem?

Yes.  If we can understand the code well enough to find how the
interrupts are cleared.

> MacsBug_6.5.3.sit.hqx   The download link is changed.
> ftp://ftp.apple.com/developer/Tool_Chest/Testing_-_Debugging/Debuggers_-_dcmds/

Thank you,
-allen

-- 
 Allen Briggs                     briggs@wasabisystems.com
 Wasabi Systems, Inc.             http://www.wasabisystems.com/