Sweet little scrolling sign and exactly what I'd been looking for. Just one problem, however. There seems to be an error in the diagram - at least as it corresponds to the code. It took me a moment to recognize it -- the display begins in the center (at the right end of U3), moves across U3, then wraps to the right end of U2 and ends in the center. Once I reversed the pinouts for columns A and B it worked perfectly.

Also, the Winblows Arduino IDE balks during compilation, saying int main (void) was redefined. Compiles without a problem in Linux, though.

If I understand you correctly, there's not actually a mistake in the circuit diagram-- it's just that we didn't say which LED display goes on the left and which goes on the right. Is that correct?

The code is in C, and so it has its own main(), unlike an Arduino sketch. If you just copy and paste it into the Arduino environment, I would expect it to *not* work.

Ahhh... Now that I take a second look, you don't have to say even that. I should have used better reasoning.

Apologies for my newbism - I mistook that part of the diagram to also be a physical layout.

You're making me have to think, man. It hurts! It hurts!