Design a 4-bit adder/subtractor (74LS283) using only full adders and XOR gates (74LS86). Do not use multiplexers. Design a combinational circuit using full adders and logic gates which will perform A...

Design a 4-bit adder/subtractor (74LS283) using only full adders and XOR gates (74LS86). Do not use multiplexers.

Design a combinational circuit using full adders and logic gates which will perform A plus B or minus B depending on a mode select input, M. If M=0, addition is carried out; if M = 1, subtraction is carried out. Assume A = A4 A3 A2 A1 A0, and B = B4, B3, B2, B1, B0. Display result on a 7 segment display using a 7 segment decoder (74LS47).