March 1, 1984

WHAT is a room - some version of which will accompany us all of our lives? Even as we hunt it or build it we seldom halt to examine further this companion to human consciousness, omnipresent as sleep or dream. Some of us, though, are bedouins in spirit until the end. How is it that the room or rooms I live in are always my favorites, yet I never think of them as the final ones - as I would prefer them to be. I even have trouble living in two Remembered Rooms This is the first article of a series that will appear from time to time in The Home Section. houses, as I presently do. They verge toward a common denominator, like any place lived in by me and mine. Both houses and their rooms offer a place to live, work, cook, eat, laugh and muse in - and both are easy on the bones and the eye. Yet they form a kind of double personality that makes me uneasy, as if I'm lying to myself a little. I was brought up to be loyal to one place. We get our room habits from our parents, or in revolt against them. Mine, by the time I knew them, were New Yorkish in the matter of moving but conservatively so - that is, they lived in the same apartment until I was 15; then changed quarters twice before they died.

Scientists have isolated a previously unknown virus and used it to infect monkeys with a disease that closely resembles acquired immune deficiency in humans. The scientists, at the University of California at Davis, believe the finding may represent an important step in determining the cause of human AIDS. Most reseachers believe the human syndrome is a result of some undetected infectious agent, presumed to be a virus. The new research appears to be the most significant laboratory achievement made so far in support of that theory.

Representative Thomas P. O'Neill Jr., the Speaker of the House, said today that he would like to retire from Congress at the end of the year and become Ambassador to Ireland ''or some place like that.'' The 71-year-old Massachusetts Democrat acknowledged that such an eventuality depended on the election of a Democratic President, which he called ''definitely in the realm of possibility.'' Otherwise, he said in an interview, ''I'll definitely leave after the next term,'' which ends in 1986. In either case, Mr. O'Neill predicted he would be succeeded as Speaker by Representative Jim Wright of Texas, the House majority leader. This would be a political shift to the right, because Mr. O'Neill considers himself an unvarnished liberal, steeped in New Deal traditions, while Mr. Wright is a moderate who, in the Speaker's words, ''is in the center of our party.''

Prime Minister Pierre Elliott Trudeau announced today that he had decided to resign after more than 15 years as head of the Canadian Government. He said it was ''the appropriate time for someone else to assume this challenge.'' Mr. Trudeau, 64 years old, whose fondness for the dramatic gesture has been as characteristic of him as the red rose he habitually wears in his lapel, made his announcement during a paralyzing snowstorm and while Parliament was in recess. But he did not do so in any public appearance.

Robert L. Crandall, the president and chief operating officer of American Airlines, said yesterday that the airline would use its new McDonnell Douglas Super 80 aircraft to build a low-cost carrier inside the old high- cost airline that could compete with other low-cost carriers. Yesterday, American confirmed reports that it had ordered 67 of the McDonnell Douglas planes in what was believed to be one of the largest orders in airline history. Although American officials would not disclose financial details, the deal is expected to be worth more than $1.3 billion. One American official said each plane would normally sell for $22 million, but because of the size of the order, the airline had received a discount. American also said it had options to buy another 100 planes.