Why the name is Transistor-transistor logic?

Answer 1

TTL - transistor-transistor logic uses connections between transistors to perform logic functions, rather than connections using resistors or diodes.

1. T - transistor input stage (logic section)
2. T - transistor output stage (power gain section)
3. L - logic

Earlier logic families like DTL (D - diode input stage) and RTL (R - resistor input stage) used different components in the input circuit and simpler output circuits.

Later logic families like IIL (Integrated Injection Logic) and CMOS (Complimentary Metal Oxide Semiconductor) used entirely different circuits without separating into input (logic) and output (power gain) stages and significantly reduced power consumption, making dramatically higher levels of integration practical.