One of the more famous of these devices is the 74181, a cascadable 4-bit arithmetic logic unit, or ALU. An ALU is the heart of a microprocessor, performing its operations. The 74181 appeared in ...

that typically came in 4-bit increments, although 1- and 2-bit devices were also made. Connected to a control unit, the ALU slices were strung together to make larger processors (8-bit ...