As far as I can tell, MIT didn't have a CS department until 1975 (when it was added to the EE department to become EECS; the same year Irene Greif in the OP got her PhD).

Before the 70s, many schools considered CS as part of a Math degree or an EE degree.

Cite: https://www.eecs.mit.edu/about-us/mit-eecs-department-facts