Pretty cool calculator. Looks like you have a pretty good handle on DataComm.

I'm going to retrofit the external osc. tonight and see what happens. I only have two osc. right now that run at 4Mhz. That has always been fast enough on my 16F628A's to get 9600. In my real time application though, 2400 might be enough.

I refined the code last night and will work on it again tonight, so I could attach it as a .txt file tomorrow.