Fortran Wiki

For your enjoyment, TOMS Algorithm 568 (PDS - A Portable File Directory System) includes a version of Ratfor:

The machine-independent version of the Ratfor preprocessor is installed by a “bootstrapping” process. The relevant files are listed in the previous section. MBOOT is a complete machine-independent ratfor preprocessor written in fortran. With the exception of hollerith literals, the fortran code in MBOOT is in upper case. It was produced by preprocessing main.rat, ratio.rat, and ratfor.rat, and concatenating the results. this file is ready for compilation.

MBOOT is compiled, tested, and installed as “version 0” of RATFOR. Modifications necessary to accomodate local conventions and usage are made to main.rat, ratio.rat, and ratfor.rat. The version 0 RATFOR is used to produce a new, presumably better, version 1 RATFOR using the modified files. This process can continue until further modifications are unnecessary.