Why Johnny Can't Compile Fortran with Subroutines

[Peter Peterson]

Hi all,

We had two problems: 

1. We couldn't compile Fortran IV code with subroutines.

2. We couldn't run FRTS successfully on the PDP-12.

This email addresses the first problem; my next email will address the second.

I also plan to get some blog posts in on this soon, but I wanted to get in touch with the group, first.

We did some digging, and I believe we have solved our Fortran subroutine problems -- or rather, someone else solved our problems. It turned out to be pretty simple, actually: it looks like Fortran IV expects subroutines and functions to be in separate files that are compiled together.

Using the instructions in this blog post:

http://pdpchallenge.blogspot.com/2015/07/some-answers-to-old-problems-and-why.html

... we were able to compile and execute Fortran IV with subroutines -- in SIMH.

Perhaps there is some way to get it to look for multiple subroutines / functions in the same source file... I don't know. But this method works.

Peter

--

Peter A. H. Peterson, Ph.D.

Assistant Professor
Department of Computer Science

University of Minnesota Duluth