simplest computer in a circuit
ram rom processor io but really tiny and simple

use case:
traffic light
 from simple red-green A+B-TB+A-T in loop
 to red-green-yellow-with-independant-crossing-button

door code lock:
 number button and a memory

alarm clock:
 maybe need a quartz for this

blinken light:
 aesthetic

roomba:
 move on its own

rc vehicle:
 obey to command with logic

segway:
 maybe need analogic

i2c comm:
 at least with a real usage

maybe programable with punch card ?