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From: brian@granite.jpl.nasa.gov (Brian of ASTD-CP)
Newsgroups: comp.lang.scheme
Subject: Re: what makes scheme?
Message-ID: <4550@jato.Jpl.Nasa.Gov>
Date: 14 Aug 90 19:25:43 GMT
References: <9008031618.AA02461@mailhost.samsung.com> <RICH.90Aug7015042@uncle-bens.Rice.edu> <1185@wrs.wrs.com> <.650536187@dutepp1>
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Reply-To: brian@granite.Jpl.Nasa.Gov (Brian of ASTD-CP)
Organization: Jet Propulsion Laboratory, Pasadena, CA
Lines: 35

In article <.650536187@dutepp1> alfred@dutepp1.tudelft.nl (Alfred Kayser) writes:
>>Platforms?
>> * VAX/VMS * VAX UNIX * SUN-3 * SUN-4 * AMIGA * MACINTOSH * MIPS * CRAY
>I've once tryed to port it to MSDOS or OS2 (compiler and cpu are the same)
>but it crashed enormously. 

    I think MSDOS/OS2 is a very special case, so your failure
    to bring up SIOD on this machine should not be viewed as an
    indictment of SIOD.  All the other platforms at least have
    Von Neumann architectures underneath.  MSDOS/OS2 runs on
    80x86 chips, which are not Von Neumann computers: almost
    every cell in memory has 4096 DIFFERENT addresses
    (segment/offset pairs)!  It is very difficult to write a
    Lisp/Prolog implementation that ports easily between Intel
    processors and the rest of the world, mostly because the
    assumption that every cell in memory has a unique address
    is implicit in implementation languages such as C and
    Pascal.  If it is not the case that every cell in memory
    has a unique address, then the programmer of a would-be
    portable program must tip-toe very carefully around pointer
    arithmetic, indirection, and address-taking operations.
    Also, the programmer must make decisions about "memory
    model": tiny, small, medium, big, huge etc.  Such decisions
    do not exist on the other platforms mentioned.

>--
>-- Ir. Alfred Kayser. PACS, OS/2, TCP/IP. --- Email: AKayser@et.tudelft.nl --
>-- CARDIT, Delft University of Technology ------------ Tel: (31)-15-786179 --
>-- P.O.Box 5031, 2600 GA Delft, The Netherlands ------ Fax: (31)-15-784898 --


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 . . Brian Beckman . . . . . . . . . . brian@granite.jpl.nasa.gov. . . .
 . . meta-disclaimer: every statement in this message is false . . . . .
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