Can somone please tell me what 128 is in binary.

if -128 = 10000000
and we apply (-n = ~n + 1)
we get 01111111 which is 127 + 1 = 128

but what is 128 in binary? If 127 = 01111111 then
adding one 11111111 gives us 255 not 128.

As much as i love my calculator i cant seem to rely on it
for numbering conversions. for 128 it gives me 10000000
and for -128 it gives me 1110000000. I dont know
why it seems to add stuff.

also i have a book which says that -128 in Hex is
0x80 but as far as i can see that's 128 not -128

8*16^1 = 128
0*16^0 = 0