I was a young kid when these came out. I remember being in a store that had one running around as a demo, bumping aimlessly around under shelves and off shopper's feet. With amusement, I watched it bump off a table leg, and rotate perfectly into position to drive through the open front door, then slowly drive forwards out of the store, never to be seen again.

Not long after that is when I started reading hardware hacking stuff. The early Roombas were extremely hackable - each one had a serial port connector under a cover and you could connect it to a computer and drive them around. It was the pre-Raspberry Pi days; I remember people attaching a router or the lightest netbook they could find for some sort of wifi remote control.

I was too young to ever get to play with one, but I did get to take a broken one apart once. Some highlights were the planetary gearbox contained inside the wheel hubs, and a cam on the rear caster which would trigger an optical limit switch once per rotation so it could estimate distance traveled.

That original half-black/half-white caster for very simple/cheap optical limits was something of a known off-the-shelf approach. You'd often use them in various Lego Robotics environments a decade or two before the Roomba.

It's easy to agree with the article here that the off-the-shelf simplicity of the early Roomba was a virtue. I appreciated that sense that you could look at a lot of the parts and guess what they were for or how the operated from the software side. That caster was one of those for "oh, yeah, that's probably for simple distance estimations".