FORTRAN is one of the earliest high-level languages, arguably the first. Our main interest is its place in the early history of programming languages, and the notes present an early style FORTRAN program.
FORTRAN has developed considerably since its first days and now has much more modern forms. There is a FORTRAN font end for gcc which is probably available as part of your Linux distro. There is also Windows version available, and you can even install a verson of CodeBlocks which includes it.