Complex sentence: In 1979, William Yerazunis wrote a partial version of APL in Prime computer FORTRAN, extended it with graphics primitives, and released it; it was also the subject of his Masters thesis.
Split into simpler sentences: In 1979, William Yerazunis wrote a partial version of APL in Prime Computer FORTRAN, extended it with graphics primitives, and released it. This was also the subject of his Masters thesis.