[SubMareener]

Is there a negative zero?

Yes. In ones-complement binary arithmetic all zeros represent positive zero and all ones represents negative zero. Most computers, today, use twos-complements arithmetic where all zeros represents zero and all ones represents minus one.

[GingisK]

Incorrecto... There is no negative binary zero. Binary numbers are a "two's complement". The leftmost bit is the sign. For example:

Minus one is 11111111 (One byte)
add one: 00000001
result: 00000000, with the carry bit set in the status register

Now take zero 00000000
subrtact one 00000001
result: 11111111 (minus one), with the carry bit set in the status register

Carry bit set after a subtraction, you ask? Yes. Two's complement subtraction is done by complementing the bits and adding, and then adding another one.

[BEJ]

Thanks for that info.