00000000
0 (assume a borrow is possible)- 00000001
- 1----------
-----????????
100000000
0 (show the 1 that will be borrowed)- 00000001
- 1----------
-----11111111
-1 (two's complement)11111111
-1 (two's complement)- 00000001
- 1----------
-----11111110
-2 (two's complement)11111110
-2 (two's complement)- 00000001
- 1----------
-----11111101
-3 (two's complement)10000001
-127 (two's complement)- 00000001
- 1----------
-----10000000
-128 (two's complement)