With my 65816 system up and running, I can now start working on add-in cards. A simple one to start: an LCD. I designed the PCB to be somewhat flexible. In the example below, I connected a two-line LCD along with a bar graph. The LCD is connected to VIA #2 Port A. The first eight LEDs on the bar graph are tied to VIA #2 Port B, the ninth LED isn't used, and the tenth LED is connected to power.
I've found this card to be handy when I want to do some debugging. I can plug in the card, send debugging output to the LCD and/or bar graph, and then remove the card when I'm done debugging.
Side note: If I want more than one card, I just connect to a different address line. This card is setup on A14. I could quickly add additional cards on A13, A12, and A11. The remainder of my $10:000 I/O range will go to my sound card. If four VIAs aren't enough, I can add another I/O range.