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To: linux-kernel@vger.kernel.org
From: "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: how to tell Linux *not* to share IRQs ?
Date: 6 Nov 2001 15:17:12 -0800
Organization: Transmeta Corporation, Santa Clara CA
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In-Reply-To: <3B6E44EE000F26DC@mta1n.bluewin.ch> <Pine.LNX.4.31.0108081515300.3853-100000@rc.priv.hereintown.net>
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Copyright: Copyright 2001 H. Peter Anvin - All Rights Reserved
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Followup to:  <Pine.LNX.4.31.0108081515300.3853-100000@rc.priv.hereintown.net>
By author:    Chris Meadors <clubneon@hereintown.net>
In newsgroup: linux.dev.kernel
>
> On Wed, 8 Aug 2001, Per Jessen wrote:
> 
> > Yeah - I believe the same was possible on the Z80 - though I'd have to
> > go read the manual to be certain.
> 
> It is.  When I was reading the description in the previous e-mail, I was
> thinking, "that sounds a lot like the Z80".
> 
> I missed the beginning of this thead, what did the so old its new mean?
> Is there a new chip supporting vectored interupts?  Or are they just being
> simulated in software?
> 

The x86 supports vectored interrupts, too (at least in the same sense
the Z80 does.)  There are 256 interrupt vectors possible, 32 of which
are reserved (although that didn't keep IBM from foolishly use them
rather than the 224 that weren't...)  However, the PIC architecture in
the PC doesn't use this -- it lets the vectors be generated by the
PIC; the standard dual PIC allows only for 15 vectors and the APIC
something like 24, and it's all controlled by which input line gets
pulled.

Sad, isn't it?

	-hpa

-- 
<hpa@transmeta.com> at work, <hpa@zytor.com> in private!
"Unix gives you enough rope to shoot yourself in the foot."
http://www.zytor.com/~hpa/puzzle.txt	<amsp@zytor.com>
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