Re: ALU, negationx, y, add16 off by one?

Posted by milythael on Dec 06, 2011; 4:59pm
URL: http://nand2tetris-questions-and-answers-forum.52.s1.nabble.com/ALU-negationx-y-add16-off-by-one-tp3564869p3564913.html

It seems as though you have a misapprehension about the twos
complement notation.  not x (where x is positive) is not equal to -x.
I think this might best be explored with 0.  Obviously,
mathematically, -0 = 0, however, in twos complement, not 0 = -1.

On Tue, Dec 6, 2011 at 10:48 AM, rogerdodger91 [via TECS Questions and
Answers Forum] <[hidden email]> wrote:
> So when im adding positive x, to positive y. And I negate either one and set
> f to 1. Is it right that the result is a number that is one less compared to
> the result i would have gotten if I used a negative sign instead of the
> negation bit?