Some more reading that coincidentally came up in an IEEE post.

https://spectrum.ieee.org/the-institute/ieee-history/three-chips-in-one-the-history-of-the-bcd-integrated-circuit?utmsource=theinstitutealert&utm_medium=email&utm_campaign=theinstitutealert-06-22-21&mkt_tok=NzU2LUdQSC04OTkAAAF906idzq40e3x8DKdkMYOce531yCvfNsHR--b_Lt-iXqUrOBTXHWYJswgmdmiLnLOTwWgO6AjqgfgH0Pu_Br-GsOToxHLctAw8FNXCf1SK5Yw