Casio College fx-80 : which IC hides inside ?

[damaltor]

Well, to get to know what ic is in your calc without opening it, you might try the "calculator forensics":
http://www.rskey.org/~mwsebastian/miscprj/forensics.htm
if you follow the mentioned steps and compare your results to the table, you might get a hint by looking at other calcs with the same forensic result value, and look which chips hide inside those.