Terminated: unknown
I have also found a COMPEX SR-40, but the one I found is broken and I haven't therefore added it to my calculator collection. The circuit board of the SR-40 is identical to the circuit board of the SR-55. The difference is that the SR-40 lacks all scientific functions from the keyboard.
The "y^x"-key performs the decimal log of a number.
The fluorescent display is oriented left-to-right, meaning that when you type a number the first digit shows up on the left side of the display, and following digits are appended at the right.
This calculator has some nice display features as well:
When the calculator's memory stores a non-zero value, the bottom-right
segment of the leftmost digit of the calculator's display lights up, as
shown on the example on the right.
And when the calculator's has a pending parenthesis (out of a maximum of
2 pending parenthesis operations), the top-left segment of the leftmost
digit of the calculator's display lights up, as shown on the example on
the right.