Roger B. Sorrells was a born tinkerer who adapted his skills to help a generation of graduate students solve their software problems.

"His family tells me that when he was a little boy, he was enormously curious about how things worked," his longtime partner, Gloriana St. Clair, said. "If that meant he had to take his toys apart, he took them apart."

Decades later he assisted students working in multiple fields at Texas A&M University to find errors in their computer programs. Debugging software was critical to completion of their doctoral research projects, said Ms. St. Clair, dean of libraries at Carnegie Mellon University.

Mr. Sorrells died Friday at Schenley Gardens from the effects of advanced-stage Parkinson's disease. He was 74.

He moved to Pittsburgh about three years ago, after his Parkinson's symptoms worsened, and he had been a regular visitor here for more than a decade.

"Any student ... who had a glitch in a computer program that nobody else could identify remembers Roger's 'deus ex machina' ability to put his finger precisely on the one line of code and say, 'Here's the problem,' " recalled R. Douglas Spence, who was one of those students, completing his Ph.D. at Texas A&M in 1986.

Ms. St. Clair said she was preparing a reading for a luncheon planned to celebrate Mr. Sorrells' life called "Roger's big brain." His passion for science, mathematics and reading was matched by his love of strenuous exercise and the outdoors, she said. "He was very smart, very funny and very fit," she recalled.

Hal Manzke, a retired math teacher from San Antonio, Texas, said Mr. Sorrells served as his mentor since they first met in 1965. Mr. Sorrells was then teaching mathematics at San Antonio College and Mr. Manzke was one of his students. "He taught me how to take engines out of a VW and how to canoe," Mr. Manzke said. "Before I went on my first job interview, he gave me a haircut and loaned me a suit."

The two made many trips together as Mr. Sorrells pursued his love of walking, hiking, biking, cave exploration and snorkeling. The two had their last visit together at Schenley Gardens on the evening before Mr. Sorrells died.

"My wife and I each told him what he meant to us and how thankful we were to have known him," Mr. Manzke said.

Mr. Sorrells was born in Plaquemine, La., southwest of Baton Rouge. He was the son of the late B.J. and Maurine C. Sorrells. He earned a bachelor's degree in physics and a master's degree in mathematics, both from the University of Texas. Besides teaching at San Antonio College, he also taught at what was then Southwest Texas State University in San Marcos.

Changing careers, he began work on a Ph.D. in computer science at Texas A&M University in 1971. He made the switch after San Antonio College purchased a Digital Equipment Corp. PDP11 computer, and he was given permission to work on the new device. "They let him play with it and he fell in love with computing," Ms. St. Clair said.

While he never completed his Ph.D., he joined Texas A&M's Computing Center in 1978, eventually becoming chief of its Help Desk. He received the university's President's Meritorious Service Award in 1991. He retired the next year.

In 1961, he married Cynthia Hammond Wickizer, and the couple had a daughter, Alexandra. They later divorced. In 1984, he met Ms. St. Clair, then a librarian at Texas A&M.

In later years, he traveled with Ms. St. Clair and CMU's Raj Reddy for the Million Book Digital Library Project, a successful effort to create an online, free-to-read resource of more than 1 million volumes.

He was a founding member of the Highlands Circle at CMU, a society for donors who contribute $1 million or more to the university during their lifetimes or through their estates.

In addition to Ms. St. Clair, his survivors include his brother, Mike, of Dallas. His daughter died in 1982, the victim of a drunk driver on New Year's Eve.

Memorial lunches will be held in Bryan-College Station, Texas, and in Pittsburgh. Memorial bike rides are planned for Texas's Hill Country, near where he lived and worked for many years, and in Washington, D.C. Friends interested in participating are asked to contact gstclair@andrew.cmu.edu or zke@swbell.net.

Memorial gifts may be made to Carnegie Mellon University Libraries, Hunt Library, Dean's Office, 5000 Forbes Ave., Pittsburgh 15213, or Mothers Against Drunk Driving, Western Pennsylvania Office, 222 W. Cunningham St., Butler 16001.

Arrangements are by John A. Freyvogel Funeral Home, 4900 Centre Ave., Pittsburgh.