Apple Pascal is an implementation of Pascal for the Apple II and Apple III computer series. It is based on UCSD Pascal.Just like other UCSD Pascal implementations, it ran on its own operating system (Apple Pascal Operating System, a derivative of UCSD p-System with graphical extensions). Originally released for the Apple II in August 1979, just after Apple DOS 3.2, Apple Pascal pioneered a number of features that would later be incorporated into DOS 3.3, as well as others that would not be seen again until the introduction of ProDOS.