ProBASIC enhances the Applesoft BASIC that is built-in to your Apple II computer. New commands and functions can be added to your programs. Programmers familiar with structured languages such as Pascal and C will quickly see the similarities between a ProBASIC module and a procedure or function. - Modules may be written in BASIC or Machine Language. - BASIC modules add modularity and structure that make it much easier to edit, debug, and maintain your programs, while Machine Language modules greatly increase the speed of your programs. - Variable conflicts are easier to avoid since each BASIC module has its own set of variables. - Modules may be saved on disk and easily integrated into other programs.