[bsder]

While two's complement is quite clever, it's not an obvious choice when you are building things out of tubes or relays.

One's complement has two very nice properties:

1) the range is symmetric

2) "end-around carry" makes all the bits look identical in terms of implementation

[bogomipz]

But isn't that drawback of 1's complement that 0 in an 8 bit number can be represented two different ways?

0000 0000 and 1111 1111

[bsder]

Is it a drawback? If your "compare to 0" is "are all bits the same", then it would be an advantage.

An asymmetric range is a "drawback" of two's complement. Is that a drawback?

It depends upon what your building blocks in the technology are. For example, we don't use J-K flip flops anymore because they are a pain to make and use when MOSFET's are your building blocks (J-K wants bipolars).