Our website provided a free download of rpnCalc 1.6.1 for Mac. This free software for Mac OS X was originally developed by Rick Lansky. The program relates to System Tools.
From the developer:
rpnCalc is a reverse polish notation (RPN) calculator. The stack behavior is based, rather loosely, on the HP-28S. rpnCalc offers commands which allow the stack values to be copied onto the clipboard. This functionality makes use of the pbcopy system-level command.
You may want to check out more software for Mac, such as iPhotoMini, MIXPOD.com Music Player or KanakaDashboard, which might be similar to rpnCalc.