The Baltimore Orioles will play their entire 1980 home schedule -- 81 games -- in Baltimore, the team's new owner, Edward Bennett Williams, announced tonight.

At an impromptu press conference outside his box just prior to the Orioles' game with the Minnesota Twins, Williams said he had made the decision "after talking to a number of people in Baltimore and taking some advice. But the major part of the decision was mine.

"There will be no games in Washington next season," he continued. "That includes any presidential opener. We will play 81 dates here in Memorial Stadium.

"Baltimoreans are demonstrating that they can and will support this team. I don't believe this is a one-year phenomenon. I believe it's a new dedication, the beginning of a new era of baseball enthusiasm in Baltimore."

Williams also said he has set no attendance goals for Baltimore in 1980.

Williams, who is president of the Washington Redskins, is a Washington attorney with residence in Potomac. There had been speculation since it was announced Aug. 2 that he had purchased the team that he would take advantage of a clause in the team's lease at Memorial Stadium and play up to 13 games at RFK Stadium.

But the Orioles' exceptional play, record attendance (1,322,574 spectators for an average of 22,417 per date), and pressures from many Baltimoreans were factors too strong and numerous for Williams to ignore.

Williams refused to make any commitments beyond 1980. He also would not comment on his reaction to the idea of a National League team moving into RFK Stadium.

"I'm not saying anything beyond the announcement about next season," Williams said.

"I have felt a lot of pressure both from Washington and from Baltimore since the day I signed the contract to buy this team," Williams Baltimore to Keep All 1980 Dates said. "But now that I've made the decision, I don't feel any pressure because I know it's the right one."

Williams' decision to play all 81 games here next year appears to put to rest any realistic possibility of the Orioles playing any games in Washington before 1982. Historically, baseball teams that have had resurgent seasons on the field and in attendance as the Orioles have had in 1979 -- do even better the following year because they get off to a fast start in attendance.

Thus, for the same reasons that Williams decided to keep the team here next season, he would appear to be a strong bet to do the same thing after next season.

Tonight's announcement had been expected ever since team General Manager Hank Peters said 11 days ago that he expected the club to play all its home games here next season.

Williams said he had spoken with "a number of Baltimore's business leaders who have committed to me the kind of support in the sale of season tickets for 1980 that will insure our success at the gate."

He also said that he had not asked Maryland Gov. Harry Hughes or Baltimore Mayor William D. Schaefer for any commitments in terms of renovating Memorial Stadium. "I have not asked them or any other public official for any commitments," Williams said. "I'm not looking around for any handouts."

Robert F. Sigholtz, general manager of the D.C. Armory Board facilities, expressed some dismay over the announcement but still encouraged an optimistic outlook for Washington fans.

"Naturally, I'm disappointed. I would have liked to have had some of their games. I know their contract allows for 13 games to be played here," Sigholtz said. "But I know Mayor (Marion) Barry, who is chairman of the Armory Board is anxious to acquire a baseball team for Washington. If Baltimore is not available, I'm sure he will pursue other franchises.

"If someone isn't doing very well where they are and if the Armory Board were to offer an attractive contract, it could encourage those teams to come here. And there's also the possibility of expansion in the National League.

"We have lobbied with other teams to come here," Sigholtz added. "We have kept a low profile doing it, but we've still let it be known that we are interested in acquiring a team."

He expressed no bitterness over losing a chance to showcase the Orioles at RFK Stadium.

"We were just hopeful that we might get some of those (Oriole) games here," Sigholtz said. "The way they're drawing in Baltimore -- being in Mr. Williams' shoes -- it could conceivably alienate the Baltimore fans were he to move their games. I don't think he has alienated the fans here (in Washington). A study has shown that a minimum of 15 percent of those who attend Baltimore games come from the Washington area.

"Anybody is interested in a winner, I don't care who or where it is. As a businessman, he (williams) made the right business decision. But that still doesn't say we aren't disappointed."

Washingtonians who have been involved with trying to bring a baseball team to RFK Stadium in the past expressed disappointment with the announcement but did not seem to think it meant the Orioles have no future in Washington.

"When Ed bought the team we were all excited about him bringing it to Washington for the 1974 season. "But you have to place a franchise where you have support. You'd be foolish to leave a market which is fulfilling its responsibilities to the franchise to move somewhere where you don't know what to expect,"

But Danzansky added that he and his father still were hopeful that the Orioles will eventually split their schedule between Washington and Baltimore.

"I don't think we should do anything really drastic until we know more about what Ed's going to do with the Orioles," he said when asked about the possibility of seeking a National League team.

Williams said he would be interested in talking to Prince George's County Executive Lawrence J. Hogan about a letter Hogan wrote him proposing the idea of a stadium in the Laurel area.

"I have not talked to Mr. Hogan but I'm interested in talking to anyone who has an idea which could help the Orioles," Williams said. "I must admit that, like everyone in baseball, I guess, I dream of a perfect major league baseball stadium, exclusively for baseball. It's kind of like my Walter Mitty dream."

Williams said that he had talked with Commissioner Bowie Kuhn, who has been trying almost since the day the Senators left Washington in 1971 to get baseball back to Washington, about his decision. "I don't know how the commissioner took the decision," Williams said. "I see no reason for him to be anything but satisfied with it."

Oriole President Jerold C. Hoffberger, who joined Williams in his box after the announcement, termed the decision "a great one." He also said that he had made up his mind about whether to stay on as team president, but was not yet ready to announce his decision.