SoylentNews

owl [soylentnews.org] writes:

Going through a collection of old parts, CuriousMarc encountered some ICs that he couldn't identify. He opened up one of these ICs, and I studied it under the microscope. After some reverse engineering, I determined that it was a logic chip that implemented four NAND gates using old-fashioned diode-transistor logic (DTL).1 The chip turned out to be the ST680A, a member of the Signetics 600 series of chips from 1965. In this article, I discuss the circuitry in this chip and how diode-transistor logic works.

Original Submission