Callahan joined Microsoft in late 2005. He is part of a cross-divisional team that is looking forward to the coming surge of multi-core processors that will make parallel-computing ubiquitous in home and office. This is a tremendous opportunity for Microsoft to exploit this fundamental shift in programming and how systems will be used to enable new user experiences and capabilities in all our business areas. Callahan’s particular strengths are in programming languages, programming techniques, and compilation techniques focused on expression and exploiting concurrency. Now is an exciting time as the requirements to support concurrency will affect all parts of our software.

Callahan graduated from Rice University in 1987 with a doctorate in computer science. His focus area was the use of compilers to automatically parallelize programs and the role of whole-program analysis to facilitate that process. From 1988-2000 he worked for Tera Computer Co. where is lead the development team that produced the programming environment for a novel highly multi-threaded, scalable shared memory system. This environment incorporated programming language extensions, runtime support systems, and sophisticated compilers to enable user to write efficient and scalable parallel programs. In 2000, Tera acquired Cray, and Callahan continued in an architect role at Cray Inc. The last project that was part of the DARPA funded High-Productivity Computer Sciences initiative that was aimed at advancing both system architecture and programming environments to make a qualitative improvement in the value of large systems. This project involved language design, execution models, and hardware support aimed at this goal. Callahan has been part of professional and academic activities over the years. This includes many roles on program committees for conferences and workshops as well as the occasional publication of research results in compilers or languages. He has a number of patents that resulted from work at Tera and Cray, particularly in the areas of compilers and hardware-software co-design. He is a member of the ACM, off and on. Callahan is a sometimes-duplicated bridge player.