Early CDs were labeled as to the processes used, a 3 letter code As and Ds, so:

AAD == Analog recording, Analog mastering, Digital media

ADD == Analog recording, Digitally re-mastered, Digital Media

DDD == Digital recording, Digitally re-mastered, Digital Media

This is known as a SPARS Code: https://en.wikipedia.org/wiki/SPARS_code

Your dad's friends should have imported from Japan --- they were big on Jazz, and a lot of my Jazz CDs have spines labeled in Japanese on one side and English on the other.

Late 80s or early 90s there was also a DAD type, which often sounded really good.

From that Wiki link-

In practice, DAD was very rare, as many companies (especially the well-known classical music labels) used digital tape recorders (which were not prohibitively more expensive than analog tape recorders) during the editing or mixing stage.