Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!mips!samsung!munnari.oz.au!comp.vuw.ac.nz!actrix!templar!jbickers
From: jbickers@templar.actrix.gen.nz (John Bickers)
Newsgroups: comp.sys.amiga.advocacy
Subject: Re: 8-bit death
Message-ID: <3626.tnews@templar.actrix.gen.nz>
Date: 11 May 91 14:18:58 GMT
References: <2945.tnews@templar.actrix.gen.nz> <mykes.2364@amiga0.SF-Bay.ORG> <3474.tnews@templar.actrix.gen.nz> <1991May9.191412.15264@midway.uchicago.edu> <3515.tnews@templar.actrix.gen.nz> <1991May10.183627.29486@neon.Stanford.EDU>
Organization: TAP, NZAmigaUG.
Lines: 45

Quoted from <1991May10.183627.29486@neon.Stanford.EDU> by torrie@cs.stanford.edu (Evan Torrie):
> jbickers@templar.actrix.gen.nz (John Bickers) writes:

>   If I recall correctly, isn't this how Unix handles system entry calls?

    Ok, couple of serious points/questions here...

    .   What is the performance of this kind of system call like for
        a given CPU? I imagine that on a 680x0 more processing will be
        done as a lead-in to the function call (like the DOSBase
        functions), but is the TRAP faster than a JSR (not according
        to my assembler manual, but I may be misreading it)?

    .   Surely for Unix this would vary from implementation to
        implementation. Does it? Is this what the NeXT and A/UX use?
        Does AT&T Unix VR4 on the Amiga also do this?

> My recollection of PDP-11 V7 Unix was that all system calls were invoked 
> via a trap instruction, with a word afterwords encoding which call was

    Perhaps that was the best way to do it on a PDP-11. What are some of
    the same folks doing now with Plan-9 on modern hardware?

    What other considerations are there? I looked up the assembler for
    the PDP-11, and it appears a TRAP is a bit slower than a JSR. Is
    there something to do with the state of the machine that is useful
    to OS functions when a TRAP is used instead of a JSR (for a PDP-11,
    or for a 680x0?)?

> >    Well, the ST thing has desensitized me, otherwise I'd fall over
> >    backwards laughing at this one. I guess this is well hidden by Mac
> >    C compilers etc.
> 
>   Like I say, isn't this how Unix does it?  

    If it is, it is also well hidden by the system (as it should be)
    compilers. MS-DOS's aren't.

    In any case, I'm surprised. Is the Amiga OS the only rational one
    in this bunch, eh?

> Evan Torrie.  Stanford University, Class of 199?       torrie@cs.stanford.edu   
--
*** John Bickers, TAP, NZAmigaUG.        jbickers@templar.actrix.gen.nz ***
***         "Endless variations, make it all seem new" - Devo.          ***