Terminated: unknown
The PRINZTRONIC SR99M is a small and nice calculator from the
nineteen-seventies. It has memory, a change-sign key, and the
square root function. The "RM"-key pressed twice will clear
the calculator's memory. When something non-zero is stored in the
memory it is indicated by the leftmost decimal dot on the display.
Thanks to Wytse Hajonides for donating this calculator to my museum. He wrote me this letter (in Dutch):