Reverse-engineering a tiny 1980s chip that plays Christmas tunes

.hilite {cursor:zoom-in} a:link img.hilite, a:visited img.hilite { color: #fff;} For the holidays, I decapped a chip that plays three Christmas melodies. The UM66T melody chip from the 1980s was designed for applications such as greeting cards and toys. It looks like a transistor, but when connected to a battery and speaker it plays music. The die photo below shows the tiny silicon chip that I reverse engineer in this blog post. The UM66T die under the microscope. Click this (or any other...

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