Robert Holmgren made it possible to run the OED software on many systems
that could not run it otherwise, so it's probably appropriate to post
some further information about it here. I've got the OED 4.0 software
running on current versions of macOS, but, to use this version, you will
have to supply data files from your existing copy of the OED 4.0
software. Details here:
http://www.columbia.edu/~em36/oed40mac.html