Complex sentence: The original version was the integral and unnamed system software first introduced in 1984 with the original Macintosh, and referred to simply as the System software, which is credited with popularizing the graphical user interface concept.
Split into simpler sentences: The original version was the integral and unnamed system software first introduced in 1984 with the original Macintosh, and referred to simply as the System software. This is credited with popularizing the graphical user interface concept.