I remember using a ceramic microcontroller with the EPROM socket on top back in the 80s. It was for one of the 8051 family and it cost something like $270 to emulate the functionally of a $10 programmable CPU. The problem is that back then, the programmable CPU was one time programmable only. To do development, you burnt a new UV eraseable EPROM, put it in the ceramic chip, and put the previous EPROM chip in the UV eraser.
These expensive ceramic chips disappeared as soon as electrically erasable rom was developed for microcontrollers.