WORTH NOTING ON TV

* FRIDAY

20/20 (ABC, 10-11 p.m.): Alarming charges brought by a Saudi diplomat seeking political asylum in the United States are detailed in an interview with Barbara Walters.

Mohammed A. al-Khilewi, the former First Secretary to Saudi Arabia's UN Mission, who is now in hiding, claims the Saudis funded terrorist groups, conducted espionage against American bases, and were guilty of a range of offenses. He produces documents on the show. * SATURDAY

Gettysburg (TNT, 8-11 p.m.): The massive film dramatizing this crucial 1863 Civil War battle, as seen through the eyes of leaders on both sides, is getting its TV premiere over two consecutive nights (and is also available on home video).

The historic engagement - history's bloodiest in terms of American casualties - has never been the subject of a full-length movie before, according to its producers. They also say the final episode, the charge of a Confederate division under Maj. George Pickett, may be the single largest-scale historical scene filmed in North America since Griffith's ``Birth of a Nation.''

In any case, the production's numbers are impressive: 100 speaking parts, 5,000 ``reenactors'' restaging the conflict on the actual site in the Gettysburg National Military Park, and three years of research and other preparation.

Among the huge cast: on the Confederate side, Martin Sheen as Robert E. Lee and Tom Berenger as Lt. Gen. James Longstreet; on the Federal side, Sam Elliott as Brig. Gen. John Buford and Jeff Daniels as Col. Joshua Lawrence Chamberlain.

(Part 2 airs Sunday, 8-11 p.m.). * SUNDAY

Wimbledon (NBC, 2-6 p.m.): No play is scheduled for this day, but taped matches from earlier in the week will be aired. (An update is broadcast from 11:35 to 11:50 p.m.) * MONDAY

Wimbledon (NBC, 10 a.m. to 1 p.m.): Coverage of early rounds. (Update aired 11:35-11:50 p.m.).

Please check local listings for these programs.