Diode logic
![Diode-transistor logic in a discrete transistor clock. The diodes at A decode 1 of 12 lines to light the seven segment displays to show the hours 1 to 12. The transistors at B drive the decode diodes and displays. The diodes at C trigger one of the 12 pairs of transistors based on the state of the transistor flip-flops at D. Additional diodes in the chain of flip flops allow this to count hours.](/Images/godic/202501/09/Diode_logic_for_transistor_clock1408.jpg")
![A diode OR Gate with positive logic truth table](/Images/godic/202501/09/Diode_OR_Ideal_Diode1408.jpg")
![A diode AND Gate with positive logic truth table](/Images/godic/202501/09/Diode_AND2_Ideal_Diode1408.jpg")
![........Diode Voltage vs Current........](/Images/godic/202501/09/Diode_approximation_of_Voltage_vs_Current1408.jpg")
Diode logic (DL), or diode-resistor logic (DRL), is the construction of Boolean logic gates from diodes. Diode logic was used extensively in the construction of early computers, where semiconductor diodes could replace bulky and costly active vacuum tube elements. The most common use for diode logic is in DTL (Diode Transistor Logic) integrated circuits that include an inverter for power gain and signal restoration.