serial-out and parallel-out shift register 4004: 4-bit CPU In April 1970, Noyce hired Federico Faggin from Fairchild in order to do the chip design. At that time the block diagram and basic ...

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.