Is should say so on the front of the caclulator (Hewlett-Packard 41CX) and on the underside of the calculator
(bottom left side on the colour label with the keyfunctions)
However, the motherboard inside may be from a different calc.
So an easy check is to see if the clock module is built-in
Make sure you remove all the modules from the back and then power on the calc (press ON once) when it powers up, you
press the yellow shift key (SHIFT appears on the display),
then press ON again. If the clock module is built-in, you'll get the time. If the machine just turns off, you don't have a CX.
Nest check is a CAT 2.
Turn on the calc, press the yellow shift key (SHIFT appears on the display) then the ENTER^ key and the 2 key.
Immediately press R/S to freesze the display. You shoudl see
-TIME 2C
or something similar.
Press SST once and check what you see
If its
-CX TIME
then its a CX for sure, if its smth like ADATE, then you have a 41C or 41CV with a time module built in.
**vp
BTW the only way to get "HP-41CX" on the display, is to type it in yourself. (OK OK, let me rephrase this for the nit pickers, reseting the calc will not get anything like this string on the display)