Newsgroups: comp.arch
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: Interrupts
Message-ID: <1989Mar25.223050.9195@utzoo.uucp>
Organization: U of Toronto Zoology
References: <28200294@mcdurb>
Date: Sat, 25 Mar 89 22:30:50 GMT

In article <28200294@mcdurb> aglew@mcdurb.Urbana.Gould.COM writes:
>- How do you dispatch the interrupt?
>    Vectored?
>    Through a single entry point?
>
>    DEAD:
>	Am I correct in saying that this is a dead issue - that
>	the "use a single entry point, since all UNIX does is
>	move everybody together" idea has won out?  Or, is it just
>	that UNIX has never been written to take advantage of
>	vectored interrupts?

Unix has exploited vectored interrupts, in modest ways, from the start.
I think you've missed the real issue here:  fancy interrupt hardware (as
opposed to fancy software handling based on information supplied by the
hardware) is an idea in decline because it's no faster than software
handling and much less flexible.  The reason why Unix implementations
tend to run everything through a single point is that the hardware's
interrupt semantics are so dismally ill-suited to what the software
wants to do.  In interrupts, as in instruction sets, the trend is to
give the software people tools rather than preconceived solutions.
-- 
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