Looking through some of the documentation for the INS807x series I found a reference to the INS8075, which seems to be similar to INS8073 but with a 4K version of tiny basic instead of the 2.5K of the INS8073. So far I’ve not been able to find any documentation on the INS8075.
I did find this page about the MC 6400 which as far as I can tell seems to be the only commercial product using the INS8073. It’s in german but just about possible to read with my very poor understanding of german.
http://norbert.old.no/extra/extra3.html