Inside a 1980s filter chip that uses switched capacitors

What happened

Sometimes it's easier to identify an IC with a microscope. While sorting a box of old ICs, CuriousMarc came across some Harris ICs labeled "...

Summary assembled by rule from the sources below

Timeline

1. 16:44
   First appeared on Hacker NewsHHacker News
2. 21:28
   Discussion started on LobstersLLobsters

Sources