There are only two classes which are strict ("no substitutions") core requirements: Computational Theory and Design and Analysis of Algorithms. However, there are three more subject areas in which PhD students must take one of a specified set of courses: for instance, one of Advanced Operating Systems or High Performance Computer Architecture (but not both). However, for next semester they were only offering Advanced OS, not HPCA, and the OS class got cancelled. There was a similar situation with the Programming Language Foundations class -- none of the alternatives were offered. I suspect someone was just being staggeringly clueless; either that, or they figure people will just take one of the two next time one of them is offered.

IDT will happily employ me in Iowa, but I can't work full time and carry a six-hour courseload. My fallback plan if I couldn't afford the move would have been to stay here, transition to a full-time position, and start socking away savings. But there's a huge difference between an $11/hr internship and a $60k developer's job.