Over lunch, I added the rest of the address lines. I was then able to read the entire cart. I was also able to send commands to it. I got some good data back, but I was unable to write to the cart. Hmm.
I tracked down the problem. Stupid me. The last thing I did with the AT29C040A was to hack in some quick test. I forgot to take it out, and it didn’t work well with the NGPC cart (as it shouldn’t). After that, I was able to write the last byte of the cart and read back what I wrote. How nifty!
So, what’s next for this thing? I’m not really sure. I will need a GUI. I think I have a developer for that task.