How can 1's complement, and 2's complement have different ranges?

[Callmelucky]

Homework Statement

How can 1's complement, and 2's complement have different ranges?

Relevant Equations

For 1's complement: -(2^(n-1)-1) till 2^(n-1)-1. For 2's complement - 2^(n-1) till 2^(n-1)-1

How can 1's complement, and 2's complement have different ranges?
For 1's complement range is for 8 bit register(where first is for sign +, -) from - 127 to 127 and for 2's complement range is from - 128 to 127.

I came accros the fact that for 1's complement we have +0 and - 0, why is that and why we don't have that for 2's complement?

Thank you.

 

[pbuk]

What does the binary value 1111 1111 represent in 1's complement? And in 2's complement? What about 1000 0000?