A coworker was taking apart his Roomba today at work and marveling at its complexity as he removed great tufts of dog hair from it.  “It’s not amazing, but it’s mediocre daily, which is better than me vacuuming well once a week” he said to another fellow skeptical of its effectiveness.  “Show me how it works” asked the second guy, so the Roomba was placed on the floor and started.

Coworker 2: I see that it navigates around, but how well does it pick up things?
Coworker 1: Let’s see.  *scatters hole punch detritus on the floor, starts Roomba*
Coworker 2: It doesn’t really pick it up.
Coworker 1: It works on the assumption that it’ll go over the same area multiple times, it’ll get it eventually.

So we waited a bit and none of the pieces appeared to be picked up.  A pen was made around the paper leavings with boxes and the Roomba was placed inside so it could go no where else and still the paper bits stayed.  Eventually, the demonstrator said “I guess paper is hard to pick up” and it was left at that.

Later, a member of housekeeping came by with a dustpan and brush and cleaned up the bits as part of his rounds.  Quieter, faster, and without much fanfare, a von Neumann machine did what was necessary to provide for itself.