Ken Shirriff writes, “A die photo of a vintage 64-bit TTL RAM chip came up on Twitter recently, but the more I examined the photo the more puzzled I became. The chip didn’t look at all like a RAM chip or even a TTL chip, and in fact appeared partially analog. By studying the chip’s circuitry closely, I discovered that this RAM chip was counterfeit and had an entirely different die inside. In this article, I explain how I analyzed the die photos and figured out what it really was.”

See the full post on his blog.