Free I/O Pins on 30b?

[jwm]

Ah cool. That is more than I thought I'd have actually plus ADC. nice.

for the USB keyboard idea I was thinking of just using an atmega32u4 board (teensy, arduino nano, adafruit breakout) and having it talk serial to the rest of the calculator and install it similarly to the available usb mod board.

Bit banging a USB client on the arm wouldn't be too hard, but without a stable crystal controlled clock I don't think it is feasable.