You'll never see another jump ball toss-up in Atlantic Coast Conference basketball, fans, unless folks grow nostalgic - or dissatisfied - after elimination of one of the sport's old basics next season.

The ACC concluded several days of meetings at Myrtle Beach, S.C., with one upshot the announcement that you may as well forget all about the center circle. At the start of games, the visiting team will put the ball in play from end court; thereafter on any play that would have called for a jump, the teams will alternate in being awarded the ball out of bounds.

And in a tight contest, final seconds, what if one player ties up another? Or you're starting overtime? Quoth Skeeter Francis, ACC information director: "If it's the end of the game and it's tied, and it's the other team's turn, you've got to live with the decision."

Southwest Conference did away with toss-ups last season, ACC Commissioner Robert James noted, and has asked the NCAA rules committee to do likewise next year.

Other developments from the ACC gathering:

The basketball tournament will return to a Thursday-Friday-Saturday format (this year the games were Wednesday-Thursday-Saturday).

The baseball tournament is being dropped, James citing conflict with final exams; the regular-season champion will represent ACC in the NCAAs.

Meanwhile, in Hershey, Pa., the Eastern Eight athletic directors voted to hire a commissioner and establish a league office (location undetermined). They also revamped the basketball tournament format to give the four schools with best records in regular-season league play first-round games on their home courts, Feb. 27, 1979. Winners advance to semifinals and finals March 1 and 3 at Pittsburgh Civic Arena. Fred Gruninger of Rutgers was elected 1978-79 president of the A.D.s, succeeding Leland Byrd of West Virginia; George Washington, Duquesne, Massachusetts, Penn State, Pitt and Villanova round out the membership - which moves up initiation of home-and-home round-robin hoop play to 1980-81 from the previously projected 1982-83.

When the day broke, observers in Athens were calling the outlook glum for Los Angeles and the IOC agreeing on terms for L.A. to host the 1984 Summer Olympics. By last evening Mayor Tom Bradley reported a "major breakthrough" he believed would assure Angelenos they will get the Games - without going into hock. The IOC president, Lord Killanin, has been insistent that the city yield to standard procedure - IOC in charge of the Games financially - while Bradley was bound by City Council and officials to keep their hand on the pursestrings. The three Ms - Montreal, Munich, Mexico City - stood ready to put the 84s in the ready facilities from '76, '72 and '68, respectively, Killanin said, unless Los Angeles saw the light. The presumed compromise should allow L.A. to present its formal bid today for a vote tomorrow

All-Met basketball guard "Easy" Ed Swails, McKinley's 6-2 smoothie, chose Seattle U. yesterday. Trainer mate Ronald Curtis opted for Campbell (N.C.); Anacostia's 6-7 Andre Adams for Ohio U. (Athens) . . . If it would ever stop raining on the Alexandria Dukes, Mickey Mantle Jr. might improve his B.A. - 0.00 (0 or 15) . . . Tonight, 7:30 at Howard Law School, Dumbarton Campus, Van Ness Street NW: Pigskin Club presents Georgetown's John Thompson its award as basketball coach of the year . . . And, 7 p.m. at Bethesda Country Club, the Duke Club of Washington honors old Blue Devil All-America basketballer Dick Groat, who went on to baseball stardom with Pirates and Cards and now is in business in Pittsburgh.