We were early adopters of the iRobot Roomba. Like so many small-appliance purchases, the first Roomba came home with me when Costco had them on sale. It did the housekeeping when I had short-term apartments on a couple on-site contracts.

As Costco put newer models on sale, more Roombas followed me home. They've served well, and gather about a deck-of-cards worth of cat fur each night.

Until they encountered Caz, Roomba-Bane.

Last week, the canny canine left a trap for the Roomba, cleverly concealing it on a brown carpet.

Like a tragic hero, the Roomba fell upon its sword, or at least it's rotating brushes, and ate the poisoned road-apple.

You get the idea.

In an episode of Firefly, Kaylee is doing stuff to the Firefly's engines when Mal asks if it can be fixed.

She replies: "Some things ya can't fix. Ya gotta get a new one."

Despite my skill and experience at Roomba cleaning, the Roomba will not run. It thinks it's on the edge of a cliff and can't move without falling over.

I've tried convincing it that this is all in its mind, that the world is flat and it won't fall off the edge.

No go. I'm afraid that I have no future as a robot psychologist.

As Kaylee said, "gotta get a new one."

Some friends like RoboRock instead of Roomba. The price for the Model Q5 RoboRock is about the same as a Roomba E6, so I decided to try the newer tech.

The Roomba can be run manually be clicking the "Clean" button. The RoboRock is only controlled via a phone app. Convincing the Rock to connect to my WiFi took a few tries, but once it synched up, it was happy,

So far, so good.

The changes in technology are impressive.

The Roomba does a random walk, and eventually cleans an entire area. It may take it a few days to find the clump of cat-hair in the middle of the room, but it will find it eventually.

The first thing I had to do with the RoboRock was to let it map out the house. It put a shoulder against the wall and traced the circumference, did some random walking to identify furniture, and then showed me a map.

For reasons best known to the Rock, its decided my house has three rooms. This works for me, since one room is the area where I've got a working Roomba, so I don't need it to clean that area, and another room is the bedroom/master bath, that I'd rather it wasn't cleaning while I'm trying to sleep.

As soon as it finished making the map, I sent it to clean the entire house, just to see what it would do.

What it did was to go back and forth, hitting every square inch of the room, not the random walk the Roomba uses. It cleaned a couple rooms, then ran out of power and trundled back to its charger for a nap.

A couple hours later, I was surprised when it started up without me asking it to do anything. It went back to where it ran out of power, and finished cleaning the house.

Cute.

That night, it did a good job of cleaning the area I wanted it to clean. You can look at the map in the phone app to see where it's been.

The only issue I'm seeing so far is inter-species rivalry.

It's important in nature to occupy your niche and deny that niche to other species.

The Roomba uses little "invisible walls" to know where it should and shouldn't go.

The RoboRock has a map and GPS to know where it is and where it shouldn't go.

So, while cleaning the area, the Rock bumped into all the portable walls and moved them. Later, when the Roomba ran, there was nothing to keep it in a safe area. It wandered far afield, ran out of power and the poor thing starved. (Until I got up and carried it to the charging station.)

Compared to the cats marking territory, I can live with this rivalry.