processor built entirely with TTL integrated circuits. Analog applications While originally designed to handle logic-level digital signals, a TTL inverter can be biased as an analog amplifier. Connecting a resistor between the output and the input biases the TTL element as a negative feedback amplifier. Such amplifiers may be useful to convert analog signals to the digital domain but would not ordinarily be used where analog amplification is the primary purpose. TTL inverters can also be used in crystal oscillators where their analog amplification ability is significant. A TTL gate may operate inadvertently as an analog amplifier if the input is connected to a slowly changing input signal that traverses the unspecified region from 0.8 V to 2 V. The output can be erratic when the input is in this range. A slowly changing input like this can also cause excess power dissipation in the output circuit. If such an analog input must be used, there are specialized TTL parts with Schmitt trigger inputs available that will reliably convert the analog input to a digital value, effectively operating as a one bit A to D converter. See also Differential TTL List of 7400 series integrated circuits References Further reading Lessons in Electric Circuits - Volume IV - Digital; Tony Kuphaldt; Open Book Project; 508 pages; 2007. (Chapter 3 Logic Gates) External links Fairchild Semiconductor. An Introduction to and Comparison of 74HCT TTL Compatible CMOS Logic (Application Note 368). 1984. (for relative ESD sensitivity of TTL and CMOS.) Texas Instruments logic family application notes Digital electronics Logic families