The Diode-transistor logic reference article from the English Wikipedia on 24-Apr-2004
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Diode-transistor logic

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Diode-transistor logic (DTL) is a class of digital circuits built from bipolar junction transistors (BJT), diodes and resistors; it is the direct ancestor of transistor-transistor logic.

See also: resistor-transistor logic (RTL), transistor-transistor logic (DTL), emitter coupled logic (ECL).