“I dissolved the epoxy package in boiling sulfuric acid to expose the silicon die inside.”
The UM66T looks like a transistor and plays Jingle Bells when you hook up a battery and a speaker. It was made for greeting cards and toys. Inside there’s no microcontroller, just flip-flops, gates and a 64-note melody ROM. Somebody engineered all of that so a card could beep, and it still beats most of the smart toys sold today.