On Thu, Sep 24, 2020 at 6:20 PM Greg 'groggy' Lehey <grog@lemis.com> wrote:

> On Wednesday, 23 September 2020 at 22:33:38 -0400, Clem Cole wrote:
> > Dave: Seymour used ones complement on the 3000 and 6000 series.
> > Maybe there?   The primary HLLs I used on the CDC boxes were FTN and
> > Pascal, but I would not be surprised if that was were you saw it.
>
> I think most of the bigger pre-IBM 360 machines used one's complement.
> Didn't the PDP-10?  I knew it not only from the CDC 3200 and 3800, but
> primarily from Univac (1108 and 494).  The Univac techies explained to
> me that the primary arithmetic function was subtraction; addition was
> subtracting the complement.  And that worked faster with one's
> complement.
>

Don't know about the others, but I'm pretty sure PDP-10 wasn't 1's
compliment / was 2's compliment..

Warner