Place the folder "HP15C hide ƒ" anyplace you like, although in the system folder is convenient. Inside this folder are two other folders, named "Newer ƒ" and "Older ƒ". Inside each of these is a file named "HP15C_Program". Running the calculator program will create a file with this name in the system folder. At any time you may replace that file with one of the two mentioned above from the distribution. Before you do this, however, you should, if the calculator app is running, close the open program file by selecting the Close Program item from the file menu. Option-click-drag will create a copy of the distribution copy which will replace the one in the system folder if it exists. After doing this, load the new program file by selecting the Load Program item from the file menu. Each of the files contain a program in HP15C language which I created to test the programmability function of this calculator. The program steps may be viewed by entering program mode, which is done by clicking on the button labeled "g", followed by clicking the button "R/S". Click the button "SST" repeatedly to see the code of the program. When done with this, re-enter run mode by clicking again the sequence "g R/S". Run either of the programs from "USER" mode(USER mode may be toggled on or off by clicking the button sequence "f RCL") by clicking on the button in the upper left corner labeled with the "square root of x" symbol. You are in USER mode if the word USER is displayed in the display area. If not in USER mode, the programs can be run by clicking the "f" button followed by the "square root of x" button.
