Frances “Fran” Allen was one of the premier computer scientists of the 20th century. Her creative thinking and persistence had a broad impact on the field, and she received its highest honors.

She was the first woman to receive a Turing Award, for her work in high-performance computing, and also the first woman to be named an IBM Fellow. When she died at age 88, on her birthday in 2020, she was lionized as a mentor and visionary. The Institute of Electrical and Electronics Engineers (IEEE) established The Allen Medal in her honor to recognize “innovative work in computing leading to lasting impact on other fields of engineering, technology or science.” It’s the second IEEE Medal to be named after a woman.

While Allen’s entry into computer science was almost serendipitous — she went to work at IBM to pay off school debts — she spent a lifetime at the company building foundations upon which countless innovations would be built. Her contributions accelerated the development of programs that use multiple processors simultaneously in order to obtain faster results. Her work also contributed to advances in the use of high-performance computers for weather forecasting, DNA matching and national security functions.

Close observers of Allen’s life and legacy have considered her something of an “accidental” scientist. Her first assignment at IBM was to teach the research community Fortran, a complex language the company had announced only months prior — which often meant learning subject matter mere days before teaching it to students. “It set my interest in compiling, and it also set the way I thought about compilers, because it was organized in a way that has a direct heritage to modern compilers,” she said.

After her work with Fortran, she became one of three designers for IBM’s Stretch-Harvest project in the late 1950s and early 1960s. Stretch was one of the first supercomputers, and Harvest was a coprocessor. As the language liaison, she helped design and build Alpha, a high-level language that helped the US National Security Agency compose new alphabets that transcended existing languages and perform codebreaking on secret messages.

Her next project was an Experimental Compiler for IBM’s Advanced Computing System (ACS), which resulted in a tool to drive hardware design and a new way to transform programs. An optimizing compiler can be used to minimize or maximize attributes of an executable computer program, including execution time, memory footprint, storage size and power consumption. As a result of her work, Allen published a seminal paper on program optimization, “A Catalog of Optimizing Transformation.” It described a powerful new framework for implementing analysis in addition to a robust set of advanced algorithms and transformations that are still in use. (In computing, transformation is the process of converting data from one format or structure into another. It’s a fundamental aspect of data integration and data management and plays an important role in repositioning computer graphics.) Allen also helped develop software for IBM’s Blue Gene supercomputer project, the system that helped map the human genome.

The computer scientist and author Guy Steele wrote about Allen’s work for the Association of Computing Machinery. “Fran Allen’s focus has not been on inventing new programming languages or language features and then trying to get people to program using them,” he said. “Rather, she focused on taking programs as programmers like to write them and made them run efficiently by doing sophisticated analysis and optimization of the code. She didn’t create paper designs, but a series of working systems that run real programs, not just artificial benchmarks, faster. Today’s programming language compilers still rely on techniques that she pioneered.”

Beyond her technical achievements, Allen brought a dynamic human dimension to the profession. She was a devoted counselor to her colleagues, and especially women, spending many years participating in the IBM mentor program. She became the first woman IBM Fellow in 1989, an IEEE Fellow in 1991 and an Association for Computing Machinery (ACM) Fellow in 1994.

In 2006, after her semi-retirement, Allen received the ACM A.M. Turing Award, which is often referred to as the “Nobel Prize of computing.” “Fran Allen’s work has led to remarkable advances in compiler design and machine architecture that are at the foundation of modern high-performance computing,” said Ruzena Bajcsy, chair of ACM’s Turing Award Committee. “Her contributions have spanned most of the history of computer science, and have made possible computing techniques that we rely on today in business and technology.”

Allen held memberships in the National Academy of Engineering, the American Philosophical Society, and the American Academy of Arts and Sciences. She was a member of the Computer Science and Telecommunications Board, the Computing Research Association Board, and the National Science Foundation’s Computer and Information Science and Engineering Advisory Board. She was at various points a visiting professor at New York University, a consulting professor at Stanford University, the Chancellor’s Distinguished Lecturer and Mackay Lecturer at the University of California, Berkeley, and Regents Lecturer at the University of California, San Diego.

In addition to the eponymous medal established by IEEE in conjunction with IBM, she received three honorary doctoral degrees, from the University of Alberta, Pace University and the University of Illinois, Urbana-Champaign. She was also inducted into the Women in Technology International Hall of Fame.

Allen’s passions included the study of environmental issues, and she was an avid mountain climber. She was a member of the American Alpine Club and participated in expeditions to the China-Tibet border and the Arctic. “All the things I do are of a piece,” Allen once reflected. “I’m exploring the edges, finding new ways of doing things. It keeps me very, very engaged.”

Her nephew Ryan McKee reflected on Allen’s achievements after she died in 2020. “Fran spent a lifetime working to advance the field of computing and pioneer new breakthroughs,” he said. “Personally, she was equally focused on inspiring and motivating young people — especially women — to do the same.”

In other words, Frances Allen scaled more than her share of life’s peaks.