diode logic (DL)
Logics are digital links that are implemented with electronic or electromechanical components. The components used for this purpose, such as diodes or transistors, must fulfill switching functions.
A very simple logic is the diode logic where diodes are used as switching elements. The structure of a diode logic( DL) consists of two diodes, which are electrically biased by a resistor. If both diodes switch, the potential at the diode anode is pulled to the reference potential. In the other circuit concept, the diode cathodes are biased to zero potential via a resistor, and when one diode switches to forward, the voltage across the resistor increases.
So there are only two basic concepts: one forms an And gate, the other an OR gate.