Circuit 3 Using a 74HCT04, 74HCT157 and a 74HCT283, draw a circuit schematic diagram for a circuit which can act as a 4-bit two's complement adder or subtractor. The output (4-bits from the 74HCT283, which should be shown on LEDs) will have the value A+B or A-B (where A and B are the 4-bit inputs which are taken from switches). A push button input (M, mode) will determine whether the circuit performs addition or subtraction if the value is 0, addition will be performed; if the value is 1, subtraction will be performed by calculating A+(-B). The circuit is similar to that shown in lecture 4 (Wednesday 6 March) except the selection of the "B" input bits as B or not(B) is to be performed using multiplexers instead of XOR gates. (The 74HCT157 is a quad 2-to-1 multiplexer with a shared select input.) The carry output should be shown on a LED also