Arithmetic and Logic Unit (ALU) 

Now we have to have a digital circuit that can perform the required arithmetic and logical operations to do our calculations, so we have to have an Arithmetic and Logic Unit or simply the ALU .

Modern computers have multiple ALUs to be able to do multiple calculations at the same time (to increase speed). Fig. m010113.1 shows the symbolic view of the ALU and its operation. An ALU has two inputs as well as selection lines. The selection lines specify the operation to be performed on the inputs.

Fig. m010113.1 Symbolic view and operation of an ALU