I started the implementation of ALU (Arithmetic Logic Unit) of my project. For while, just the Arithmetic Unit is working. Here two 4-bit full adders chip (74LS283) are used for sum operation, and  8 XOR Gates (two 74LS86 chip) for Two's Complement circuit for subtraction operation. Next, the Logic Unit will be implemented, and a circuit of selection using Multiplexers further up.