Hi; Just double checking because the manuals I have are somewhat ambiguous -- trying to be all things to all people. Given that I am using an AMD Athalon 64 x2 CPU: (N.B. I do not need an explanation of twos complement. I thing I got it.) 1) All the texts I read say something like "If you are using a two's complement system" and go on to leave other explanatory statements open ended. I have no choice do I ? Twos complement is part of the architecture of the ALU is it not? 2) This as been answered for me before, but so much is written about signed numbers, I would like to re-check. Using C programming, my system would not need or use signed numbers (integer and floating point) would it? The concern over signed/unsigned numbers is only if there exists the possibility that the C program might be later used on a system that requires signed/unsigned numbers -- right? 3) Using an operator is a distinct instruction -- isn't it? I.e int num1 = 23 int num2 = -11 int result = num1 - num2 printf("%d",result) $ 34 int result = num1 + num2 printf("%d",result) $ 12 Writing and viewing the above code is trivial. I am trying to confirm that subtracting a negatively signed integer (or floating point) is *always* a double negative resulting in addition. I have pages of explanations. What I don't have is a friend in the next cubical I can ask "This means, what I think it means; doesn't it?" -- Regards Bill