Display was not a CRT but just some LED's in an 8 x 8 matrix that was a rudimentary gage of 8031's health/activity.

What it does point out is I'll need to keep this in mind when I get to designing the ground planes on my PCB. I know that volumes have been written about this very subject. I can see why. I can only imagine in a "real-life" industrial floor, where the lighting of choice is florescent, there must be at least a dozen bulbs waiting to die a scratchy, noisy death.

"Plug on"

Carl