What do the initials TTL stand for?

• A. Resistor-transistor logic.
• B. Transistor-transistor logic.
• C. Diode-transistor logic.
• D. Emitter-coupled logic.

Answer: (B)

TTL stands for Transistor-Transistor Logic. The name reflects that transistors are used for both the input stage and the main switching elements of the gate, giving the logic its characteristic operation. This distinguishes TTL from older families that relied on diodes or resistors at the input, and from other high-speed families that use different signaling arrangements. The result is a robust, easy-to-work-with digital logic style that became the backbone of early integrated-circuit logic, famously exemplified by the 7400-series gates.