EPHRATA, Pa. (AP) _ For 41 years Bertha Brossman Blair spent every day fulfilling a promise to her dying father, working in a high-tech industry dominated by men right up to her death last week at the age of 93.

When he was dying in 1944, William Brossman asked his eldest daughter never to leave the small telephone company he founded in 1911 in the heart of Pennsylvania Dutch country.

''There was nothing in my heart that I could do otherwise. I said, 'Yes father, I will stay,''' said Mrs. Blair, president of the Denver and Ephrata Telephone Co.

''He was to me the greatest man that ever lived and I cannot ... leave this place as long as the Good Lord lets me get up in the morning ... walk in here and say 'Good Morning' to everybody,'' she recalled in an interview shortly before her death.

Mrs. Blair died Friday after suffering a stroke at an employee's retirement dinner. She had worked for the company 72 years.

''She said she was going to die with her boots on. She made that statement a hundred times. And that's exactly what she did,'' said Ronald E. Frisbie, the company's vice president and treasurer.

Bertha Blair was a pioneer, entering the industry in its horse-and-buggy days.

In her youth, she was a businesswoman and an executive at a time when women rarely worked outside the home. In old age, she kept up with rapid technical changes in telecommunications while heading a company with 32,800 customers and 160 employees.

''You don't have many people at the age of 93 running a multimillion-dollar company,'' said Francis C. Mangan, president of the Pennsylvania Independent Telephone Asssociation.

Mrs. Blair was teaching 36 children in a rural one-room schoolhouse when she joined Denver and Ephrata as a telephone operator at her father's insistence on March 21, 1913.

''I started to work for $15 a month and I was getting $50 teaching school. So I was demoted once in my lifetime,'' she said with a laugh during an interview in her office two weeks ago.

Mrs. Blair learned the business from the switchboard on up. She kept the books, compiled directories, calculated rates, and tested phone lines. At one time she even emptied pay phone coin boxes in the dead of night.

''I was brought up in a very strange manner and yet I would not give up my training for all the training young people are getting today,'' she said. ''I was heavily disciplined at home and my father always told me to do whatever your boss tells you to do.''

Mrs. Blair was named assistant secretary and treasurer in 1926 and president in 1956. She became chairman of the board three years ago.

''I went to all the conventions, all the meetings ... the workshops. I was eager to learn,'' she said. ''Many times it was not easy because I was the only woman among all those men.''

Mrs. Blair was married twice, for a total of 18 years, and survived both husbands. She had no children.

''All I ever wanted ever, ever was a husband, and that I've had very short ... the rest of my life I lived alone. That's not what I wanted,'' she said. ''I would never have worked if I had a family, because I believe in the home life.''

In recent years, Mrs. Blair and her company had to cope with the Bell System's breakup - which she bitterly opposed - and the resulting competition for long-distance service.

''At 93, I'm working harder than I ever did,'' she said.