Complex sentence: The IBM 9020 refers to IBM System/360-family computers adapted into a multiprocessor system for use by the U.S. FAA for en route Air Traffic Control in its 20 Air Route Traffic Control Centers (ARTCCs) beginning in the late 1960s.
Split into simpler sentences: The IBM 9020 refers to IBM System/360-family computers adapted into a multiprocessor system for use by the U.S. FAA for Air Traffic Control. Systems were installed in the FAA's 20 en route Air Route Traffic Control Centers (ARTCCs), beginning in the late 1960s.