4 bit Arithmetic and Logic Unit (ALU ) – Design concept Schematic Circuit Diagram
Hey there, In this section, I have made a nice conceptual circuit diagram that will help you understand how the ALU inside the computer works.
Schematic Diagram:
What is ALU?
ALU is a combination of a digital circuit that does the arithmetic operation (like Adding two numbers, subtracting, multiplying, and division) and logic operations (like AND, OR, NOR, NOT, XOR, etc)
In this project, I have made this device just for adding, subtracting, and ANDing to show you the basic concept behind the ALU unit.
The circuit explanation
In the previous section of making a calculator project, I explained the basic concept of Adder. You can visit it by this link. So, I am assuming you have read that project. In this project, I have used IC packages directly to add the number, an XOR gate is used to make it subtractor and an AND gates IC for ANDing
Manual Selection Process:
In this project, the selection process is manual, allowing you to manually choose your input options. Alternatively, you can implement an automatic selection system using a decoder IC by pressing a button. For all three operations, the logic ground of the 74HC244 IC is individually selected. You can input binary values through push buttons, and the corresponding binary output can be observed on the 74HC244. Then, a BCD-to-seven-segment decoder, such as the 4511 IC, is employed to represent the equivalent decimal number. This concept is akin to the operation of the ALU unit within a computer. If you have any questions or concerns, please don’t hesitate to reach out. You can leave a comment below or send me a direct message for further assistance.
74HC244 IC Compatibility:
The 74HC244 IC shares an identical pinout with the LS244. It is designed to have compatible inputs with standard CMOS outputs, and with the inclusion of pull-up resistors, it becomes compatible with LSTTL outputs. This octal noninverting buffer, line driver, and line receiver are specifically intended for use with 3-state memory address drivers, clock drivers, and other bus-oriented systems. The device features noninverting outputs and includes two active-low output enables. The HC244 operates in a similar manner to the HC240A.
