As an electronics rookie, one of the first things they tell you when they teach you about logic gates is ... His design has an 8-bit data bus but a 4-bit ALU, and an impressive 2-stage ...

An earlier logic chip used as a building block for CPUs. Bit slice processors used arithmetic logic units (ALUs) that typically came in 4-bit increments, although 1- and 2-bit devices were also made.