Transistor-transistor logic, Digital Circuit which receives output from two transistors.. The first semiconductors using TTL were developed by Texas Instruments in 1965. TTL Logic term is commonly used to describe any system based on digital circuitry, as in TTL monitor.

These are used for Logic GATING And Amplification purposes. TTL Devices makes use of Bipolar Transistors. e.g 7400 QUAD NAND GATE.

With NOR GATE 7402 QUAD

Original chips have numbers like SN74LSxx S-Schottky Diode helping gates to run quickly without use of large current. LS- Low Power Schottky.

With the rapid development of integrated circuits (ICs), new problems were found and new solutions were developed. DTL circuits had a common problem that it takes as much space on the IC chip to construct a diode as it does to construct a transistor