This week's book giveaway is in the General Computing forum. We're giving away four copies of Arduino in Action and have Martin Evans, Joshua Noble, and Jordan Hochenbaum on-line! See this thread for details.
That binary pattern IS -1. Because it is 2's complement. As the sign bit(the left most) is 1, so it is a negative number, in order to calculate its absolute value, you can do the following: bitwise negation first, then plus 1. So the all 1 pattern will become 000000...01.