Who would have thought that a computer programming language developed in the mid 1950’s would still be in use in the era of petaflop systems ? The fact that a programming language has been in use for so long as technical computing has changed so much is a testament to the nature of the language itself and the ability of various organizations to update it.
Fortran (or what we used to write as FORTRAN) stands for Formula Translating System. The original language was created at IBM in the mid 1950s and was created to allow scientists and engineers to write computer programs that were numerically intensive and related to the typical technical domains such as finite element analysis, computational fluid dynamics, weather prediction and modelling, etc.
About 60 years later, Fortran has been enhanced on numerous occasions and is still in widespread use. Originally, punched cards were used to input the program, long before interactive terminals or PCs. As the language evolved and was improved over time, from the original version to FORTRAN II and beyond, new capabilities and features were added to widen the appeal and to satisfy developers who required more capability.
An important milestone for a language to be accepted, compilers generated and users using is that there is some amount of standardization. FORTRAN 66 became the first industry standard version, officially denoted as X3.9-1966. Perhaps the most important and influential version of FORTRAN was the version released as a standard in 1978, known as FOTRAN 77 and was also an ANSI Standard X3.9-1978. While FORTRAN flourished because of this and with the requests of the user community, FORTRAN did not stand still. New versions were released and came to be known as Fortran 90 and Fortran 95. (Note the change from all capital letters to just the “F”). Newer versions were released and standardized and are known as Fortran 2003 and Fortran 2008. Work is being completed on Fortran 2015.
Raw computer performance on large scale systems is still measured using a combination of a few programs with Fortran based codes still being a significant workload.
The National Energy Research Scientific Computing Center (NERSC) is the primary scientific computing facility for the Office of Science in the U.S. Department of Energy. NERSC estimates that over 1/2 the hours on their systems are used by Fortran codes. This is quite amazing, given that Fortran first appeared about 60 years ago. Similar, although unconfirmed as of publication date, usage of Fortran at many of the top supercomputing centers worldwide could be expected.