I was going to say the same thing. I read "Junkbots, Bugbots, and Bots on Wheels" years ago when I was getting started in electronics. It's also how Solarbotics got started.
Incredible book. Got me building simple neural nets out of 74AC240s rather than code before it was cool. Plan to build a 5 motor walker yet this year for old times sake.
Interesting, I have seen simple neural circuits using opamps but not octal drivers.