If you have another analog input avaliable, use the pic's VCC as a reference and tie a cheap lower voltage reference to the unused pin and measure what the PIC thinks the voltage is. The PIC's VCC is: ...
About 20 years ago I used some Hitachi LCD's that were programmed with 2x by 2x numerical digits, as well as the regular small digits. The special 1/4 character symbols were mapped into some of the Ka ...