http://www.8052.com/forum/read.phtml?id=71869

And how long will that take?!

Your robot will have to stop and wait while the PC downloads the "sensor routine"
Then, having done the sensor thing, you will have to stop again to download whatever other routine the robot needs next.

While this is an interesting idea, it sounds thoroughly impractical.

I think you'd be far better to go with either:

1. "normal" code banking where all the code is in the ROM on the robot, so switching to the "sensor routine" is simply a matter of selecting the right bank in ROM, or

2. as your scheme needs a PC anyway, and a datalink to the robot, why not have all the robot software on the PC? Let the PC do all the clever stuff, and the 8051 on the robot is basically just an interface controller.