Repeat Exercise 11.2 for a signed add/subtract unit like that shown in Figure 11.41(b). Your overflow output should be a function of the subsignal and the most significant bits of the two inputs and the output.
Exercise 11.2
When adding two unsigned numbers, a carry-out of the final stage indicates an overflow. When adding two signed numbers in two's complement format, overflow detection is slightly more complex. Develop a Boolean equation for overflow as a function of the most significant bits of the two inputs and the output.