What system does a computer use to distinguish between positive and negative numbers when stored in memory?

Question

What system does a computer use to distinguish between positive and negative numbers when stored in memory?

Answer 1

they are all just a set of 1s and 0s. the computer can translate those numbers into whatever the program its using tells it to.

Answer 2

Must electronic devices that deal with negative numbers have a bit place that indicates when the number is positive or negative.  

So in the case where a computer uses a 32 bit word, only 31 bits can be used to indicate the value of the number and the other bit is a sign bit.

So 0 in the sign bit location might indicate a  negative number and 1 in this location might mean the number is positive.

This is the simplist method, but computers also use the Ones' complement method, Two's complement , Excess-N and Base −2 methods.  These are all just variations on what I have discribed.

You can read about them here; http://en.wikipedia.org/wiki/One's_compl...

Answer 3

twos  complement eg the msb of a word is used a the signed bit to distinguish +- numbers

FFFFh = -1

0000h = 0

7FFFh =32767 max  +ve value in a 16 bit word

8000h =-32768 max -ve value in a 16 bit word

Answer 4

There are various ways of storing numbers, especially between real numbers and integers.  Number types that can be positive or negative use one bit of memory to store the sign, + or -.