The reverse is true though, and I find that fascinating with Fortran. I recently learned Fortran IV to build a backpropagated neural network for the IBM 1130 (

The reverse is true though, and I find that fascinating with Fortran. I recently learned Fortran IV to build a backpropagated neural network for the IBM 1130 (1965) and was amazed to see it compile with no warning on both the punched card compiler from IBM and on a modern Fortran compiler (gfortran). Some Fortran II conventions, like the arithmetic IF, are now deprecated, but --std=legacy is all it takes to make it work.