Terminated: unknown
It has one very peculiar and distinctive feature, the cicle visible at the front. This is the battery cover, simply turn it counter clockwise so that the two dots meet, turn the calculator over and battery and compartment fall out. For some reason the compartment on this specimen is damaged, probably because of a screw driver, maybe the previous owner didn’t know how to properly open it.
Also particular is the undistinguished all clear button, it’s the black key on the third row from above.
The EXP key, for entering exponential numbers can also be used to quickly enter factors of ten. To enter the number 1000 during calculations, for instance, just enter EXP 3.