How to Build Your Own Discrete 4-Bit ALU

Believe it or not, computers existed before microcontrollers and CPUs were around. They used to be built using discrete parts including simple ICs and transistors. CPUs are arguably the center of modern electronics, whether it be a mobile device or a control circuit for a factory. With so many types of CPUs on the market (RISC, CISC, etc.), it can be difficult—if not impossible—to keep up. But how do CPUs work? What goes on inside? In this project, we will look at the mathematical core of a CPU—the ALU. Then we’ll build one!”