Terminated: unknown
The first digit of the 12-digit display is used do display the sign of a number, the latter three for its exponent and its sign. Next to showing the sign of the exponent, the digit before the exponent also indicates a non-zero value in memory by showing an upside down "u" using the top three segments. Together with a negative exponent a small "o" is shown.
At the moment this is the only COLEX calculator in this museum. At first I assumed it was an OEM brand but the COLEX name is visible on its PCB which makes it likely this is a calculator actually designed by COLEX. Calcuseum has a picture this on this page (link validated 2025-12-22). Still, it looks very similar to the Rockwell 63R with only some of its keys at different positions.
It has all the common scientific functions including the factorial function, trigonometric functions, logarithms and their inverse powers and three levels of parenthesis.
There are two modifier keys, indicated by (M), for inverse trigonometric functions and other second functions. When using the inverse trigonometric functions it is not necessary to use the second modifier key as well.
Its angular mode is determined using a slider.
The location of the
=
mr
key is a bit awkward. The only other calculator brand where I have seen this awkward position of
the = key is Rockwell (and its OEM versions), see the aforementioned
Rockwell 63R and the
Rockwell 8R on
this site.