Re: C arithmetic, was Software proofs, was Are there different

From	drb@ihatespam.msu.edu (Dennis Boone)
Newsgroups	comp.compilers
Subject	Re: C arithmetic, was Software proofs, was Are there different
Date	2023-02-12 04:37 +0000
Organization	Compilers Central
Message-ID	<23-02-041@comp.compilers> (permalink)
References	(4 earlier) <23-02-026@comp.compilers> <23-02-029@comp.compilers> <23-02-032@comp.compilers> <23-02-035@comp.compilers> <23-02-039@comp.compilers>

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 > The three index registers were 1,2, and 4, and if you specified more
 > than one, it OR'ed them together and subtracted the result, which was
 > really strange.  There were a lot of other machines with index registers
 > but none I know of that subtracted or OR'ed.  I have also been unable to
 > tell whether the OR'ing was deliberate or just a result of minimizing
 > the number of tubes that they then documented.

Not having to have the circuitry to make sure multiple registers
were never gated onto the internal bus seems like a likely reason.

But one _could_ also conceivably use multiple index registers for
multiple dimensions, with careful allocation.

De
[As I said, I've found lots of guesses but no documents. Multiple
dimensions only work if each dimension is a power of two which,
considering the 704's tiny memory, seems unlikely. My guess is the
same as yours, fewer tubes, but it's just a guess. -John]

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Re: Are there different programming languages that are compiled to the same intermediate language? Martin Ward <mwardgkc@gmail.com> - 2023-01-31 14:04 +0000
  Re: Are there different programming languages that are compiled to the same intermediate language? arnold@freefriends.org (Aharon Robbins) - 2023-02-01 08:07 +0000
    Re: Software proofs, was Are there different programming languages that are compiled to the same intermediate language? Spiros Bousbouras <spibou@gmail.com> - 2023-02-05 15:14 +0000
      Re: C arithmetic, was Software proofs, was Are there different Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2023-02-05 16:14 -0800
        Re: C arithmetic, was Software proofs, was Are there different gah4 <gah4@u.washington.edu> - 2023-02-06 13:26 -0800
          Re: C arithmetic, was Software proofs, was Are there different Hans-Peter Diettrich <DrDiettrich1@netscape.net> - 2023-02-07 14:31 +0100
            Re: C arithmetic, was Software proofs, was Are there different gah4 <gah4@u.washington.edu> - 2023-02-08 01:10 -0800
              Re: C arithmetic, was Software proofs, was Are there different gah4 <gah4@u.washington.edu> - 2023-02-09 00:26 -0800
                Re: C arithmetic, was Software proofs, was Are there different gah4 <gah4@u.washington.edu> - 2023-02-11 00:01 -0800
                Re: C arithmetic, was Software proofs, was Are there different drb@ihatespam.msu.edu (Dennis Boone) - 2023-02-12 04:37 +0000
            Re: C arithmetic, was Software proofs, was Are there different anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2023-02-08 10:19 +0000
              Re: C arithmetic, was Software proofs, was Are there different Hans-Peter Diettrich <DrDiettrich1@netscape.net> - 2023-02-10 19:11 +0100
                Re: C arithmetic, was Software proofs, was Are there different gah4 <gah4@u.washington.edu> - 2023-02-10 23:47 -0800
                Re: C arithmetic, was Software proofs, was Are there different anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2023-02-11 22:34 +0000
                Re: old floating point, C arithmetic, was Software proofs, was Are there different gah4 <gah4@u.washington.edu> - 2023-02-11 22:48 -0800
            Re: C arithmetic, was Software proofs, was Are there different Hans-Peter Diettrich <DrDiettrich1@netscape.net> - 2023-02-08 15:24 +0100
              Re: C arithmetic, was Software proofs, was Are there different gah4 <gah4@u.washington.edu> - 2023-02-09 00:37 -0800

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