An integer is stored in 32 bits, with the left-most bit being the sign bit - 1 for negative, 0 for positive. This is called
binary. A negative number is computed by the
two's complement - you switch all bits (from 0 to 1 and vice versa), then add 1.
Now -119 is in binary:
1111 1111 1111 1111 1111 1111 1000 1001
This number is calculated as follows:
119 is 1x 64 + 32 + 16 + 0 + 4 + 2 + 1, or in binary:
0000 0000 0000 0000 0000 0000 0111 0111
The two's complement leads to the above binary form of -119.
Now hexidecimal works by converting each of these blocks of 4 into a number between 0 and 15 (inclusive), with 10-15 being represented as A-F.
So the above becomes F F F F F F 8 9 - just as you had found out.