Complex sentence: Borland has released three old versions of Turbo Pascal free of charge because of their historical interest: the original Turbo Pascal (now known as 1.0), and versions 3.02 and 5.5 for DOS.
Split into simpler sentences: Borland has released three old versions of Turbo Pascal free of charge because of their historical interest. The original Turbo Pascal (now known as 1.0), versions 3.02 and 5.5 for DOS.