HP-28S

The HP-28C was introduced with 2K bytes of storage. The HP-28S replaced it a year later with 32K bytes at the same price. The HP-28S also added: Directories. Directories allowed variables and programs to be grouped together and to allow sets of variables with the same names to be defined in separate directories. To create a directory, the user entered directory name on the stack and entered the CRDIR command. The new directory would appear in the USER menu just like any other object. Directories could be nested. The top directory was HOME and the PATH command displayed the current directory path. CLUSER purged a directory including non-empty subdirectories Custom Menu. The user could define a menu of objects/commands with the MENU command and then view this menu with the CUSTOM command. Unlike the USER menu which showed the objects in the current directory, the CUSTOM menu was set by a command and stayed the same even as the user moved through the directory structure. Graphics Strings. The LCD> command created a string that contained the bits of the current LCD display which could be stored, altered, and printed. >LCD moved a string into the LCD.