Hey there , In this section i have made a nice conceptual circuit diagram that will help you to understand how ALU inside the computer works .
What is ALU ?
ALU is a combination of digital circuit that do arithmetic operation (like Adding two number , subtracting , multiply,division and logic operation (like AND , OR ,NOR,NOT ,XOR etc )
In this project I have made this device just for addition , subtracting and ANDing to show you basic concept behind the ALU unit .
The circuit explanation
In previous section of making calculator project i have explained basic concept of Adder you can visit there by this link .So i am assuming you have read that project , In this project i have used IC pakages directly to add number , and a XOR gate is used to make it subtractor and a AND gates IC for ANDing
The selection process is menual in this project ,but you can use a decoder IC to select automatic after pressing button try it your self .(look ground of 74hc244 IC is individually selected in all three operation ) . You can simply give binary input from input pins push buttons and corresponding binary output is observed in 74hc244 and then BCD to seven segment decoder 4511 IC is used to represent equivalent decimal number .That’s all the concept behind the ALU unit inside the computer .If you have any confusion please feel free to tell me . I am always with you . you can either comment below or message me directly.