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From: firth@sei.cmu.edu (Robert Firth)
Newsgroups: comp.lang.c
Subject: Re: C critisisms
Message-ID: <3737@aw.sei.cmu.edu>
Date: 8 Jan 88 15:38:12 GMT
References: <7597@sunybcs.UUCP> <1473@codas.att.com> <3686@aw.sei.cmu.edu> <1378@sugar.UUCP>
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In article <3686@aw.sei.cmu.edu>, firth@sei.cmu.edu I wrote

[BCPL has been used for]
   (b) operating systems, including Tripos, one of the best (in my opinion)
     distributed OS (sold commercially as 'Trout')

In article <1378@sugar.UUCP> peter@sugar.UUCP (Peter da Silva) writes:

  I'd have to disagree. Tripos is also sold as the DOS part of AmigaDOS. The
  use of BCPL produces innumerable headaches for programs that want to use it:
  BCPL pointers are indexes into a 32-bit-wide array based at 0. Thus to send
  an address to BCPL you have to divide it by 4 (shift right 2 places) if you
  are using ANY other languages. The BCPL orientation of Tripos makes the C
  orientation of UNIX look like a mild bias...

Thanks, Peter - I was imprecise.  What I meant to say was that I thought
highly of the concepts, design, and implementation of Tripos, having used
it from the terminal and from BCPL code.

However, the Amiga port made a decision I consider totally crazy: to
exposdet to other languages the implementation of the BCPL pointer.  The
proper place for shifts left and right is either at the interface (so the
compiler does it for you) or within the BCPL code.  To force upon the
user those BPTRS or whatever they're called was a major blunder.  Peter
is if anything too kind here.  But I still claim (albeit unconvincingly)
that this is not a defect of BCPL but rather of the way other things
were built on top of it.

And no, I'm not about to run out and buy an Amiga, for all sorts of reasons.