Yeah, I was really looking forward to run the real SHRDLU [1] (one of the first natural language understanding programs) on ITS, but also that is... challenging. As you found out, it's possible to run a demo recording of it [2], and it's quite impressive too.

[1] https://en.wikipedia.org/wiki/SHRDLU

[2] https://github.com/PDP-10/its/issues/147

I have tried several versions of SHRDLU, binary and source, but so far I haven't found one that works. Some people claim it never really worked well. Winograd himself seems to think it did, and there is what seems to be a working demo in a 1973 TV documentary. Others say it needed heavy manual patching to be somewhat usable, and those patches didn't make it to the source code files.

Do you have a link/reference to the documentary?

Yes, I've seen the sources that say it never was stable, but I assume that at least what's in the recorded demo was at some point possible to run; of course it might be coming from a long-lost source/or binary.

Terry and SHRDLU at 8:23 here: https://archive.org/details/what-about-tomorrow-on-the-side-...

See this for some more information: https://github.com/PDP-10/its/issues/425#issuecomment-145588...

The way I debug such things is to start with a trivial FORTRAN-10 program, and get it to compile, link, and run. Then start adding pieces of Empire to it, and when it stops compiling and linking, then do a binary search on the code till the culprit is found.