His Nibbler implements a 4-bit CPU using 7400 logic chips. Because he’s come up with the architecture himself he’s taking a lot of steps to check all of his work before committing to a PCB.

The 4-bit CPU has a Harvard RISC architecture built entirely from 74HCT series logic mounted on a two-sided PCB using only through-hole parts. With 2K words of instruction RAM and 2K words of ...

In the early days of microprocessors, bit slice processors ... which included the Am2901 4-bit slice ALU. See ALU. THIS DEFINITION IS FOR PERSONAL USE ONLY. All other reproduction requires permission.