On Tue, Nov 16, 2021 at 3:40 PM Koning, Paul <paul.kon...@dell.com> wrote: > > > > > On Nov 16, 2021, at 2:03 AM, Aldy Hernandez via Gcc-patches > > <gcc-patches@gcc.gnu.org> wrote: > > > > On Tue, Nov 16, 2021, 03:20 Marek Polacek via Gcc-patches < > > gcc-patches@gcc.gnu.org> wrote: > > > >> On Tue, Nov 16, 2021 at 02:01:47AM +0000, Koning, Paul via Gcc-patches > >> wrote: > >>> > >>> > >>>> On Nov 15, 2021, at 8:48 PM, Marek Polacek via Gcc-patches < > >> gcc-patches@gcc.gnu.org> wrote: > >>>> > >>>> Nitpicking time. It's spelled "ones' complement" rather than "one's > >>>> complement". > >>> > >>> Is that so? I see Wikipedia claims it is, but there are no sources for > >> that claim. (There is an assertion that it is "discussed at length on the > >> talk page" of an article about number representation, but in fact there is > >> no discussion there at all.) > >>> > >>> I have never seen this spelling before, and I very much doubt its > >> validity. For one thing, why then have "two's complement"? For another, > >> to pick one random authority, J.E. Thornton in "Design of a computer -- the > >> Control Data 6600" refers to "one's complement" to describe the well known > >> mode used by that machine and its relatives. > >> > >> Knuth, The Art of Computer Programming Volume 2, page 203-4: > >> > >> "A two's complement number is complemented with respect to a single > >> power of 2, while a ones' complement number is complemented with respect > >> to a long sequence of 1s." > >> > > > > I think you get to do a drop mike when you pull out Knuth. > > > > :-) > > If that were the only source, sure. But with authoritative sources for both > terms (with the ones I quoted being the earlier ones) at the very least there > is an argument that both terms are used. > > Some more: DEC PDP-1 handbook (April 1960), page 9: "Negative numbers are > represented as the 1's complement of the positive numbers." > > Univac 1107 CPU manual, page 2-6: "Next, the adder subtracts the one's > complement..." > > CDC 160 programming manual (1963), page 2-1: "All arithmetic is binary, one's > complement notation". > > Incidentally, these are the four of the five machines cited by the Wikipedia > article.
All sources before Knuth are clearly wrong. How could they not? Folks living in the pre-Knuth era lived without a deity. :-P
