CASIO Personal Computer FX-790P Body only Purchased over 35 years ago. I tested the operation by inserting three button batteries. (The batteries are included) It works well enough as a scientific calculator. The beeping sound can be turned on and off. It switches to RUN and WRT modes for programming, but I don't have the manual and don't remember how to use it at all, so I haven't checked beyond that. The LCD has no burn-in or defects, but the display is dim, and the characters are difficult to see unless viewed from a fairly oblique angle. (The batteries have drained since the operational check, so it's even harder to see than in the photos) Also, the screw threads for the back cover screws are starting to strip, making them somewhat difficult to turn. Please understand that this is a very old item and has been inspected by an amateur.