Thanks Giannis!

That looks like just the thing I need. I can't tell yet, but it looks like I might be able to use it for communication between more than two devices, any idea on this? Ideally the master board should be able to interface with all slave boards (6 or 7 slave boards will suffice, but up to 18 would be a bonus).

Thanks for the suggestion!

Now I'm off to figure out how to set up my 8051 with USB port as a USB device for windows to interface with.