Here I have some information about logic families Digital IC gates are classified not only by their logic operation, but also by the specific logic circuit family to which they belong. Each of the logic families have their own basic electronic circuit upon which more complex digital circuits and functions are developed. The basic circuit in each family is either a NAND gate or a NOR gate. The electronics components employed in the construction of the basic circuit are usually used to name the logic family. Many different logic families of digital ICs have been introduced commercially. Among them some of the most popular families are listed below. TTL : Transistor Transistor Logic ECL : Emitter Coupled logic. RTL : Resistor Transistor Logic. DTL : Diode Transistor Logic. DL : Diode Logic. HTL : High Threshold Logic. IIL : Integrated Injection Logic.