The HP-15C Simulator is intended to be a useful RPN calculator for your PC desktop. It therefore makes use of the features of the underlying operating system and its GUI: Programs can be saved in files, so that you need to key them in only once. Pop-up menus provide easy and fast access to many HP-15C functions and features. However, no new function, which is not supported by the real HP-15C, is added. The Simulator supports almost all functions and features of the real HP-15C. Differences between the real HP-15C and the Simulator are rather small.