Quad-Switch TTL-Compatibility

The TTL logic currently accepted as standard calls for gate outputs no less than 2.4V for logic "true" ("1") and no greater than 0.4V for logic "false" ("0") at 25°C. Corresponding to these levels are the usually-specific logic input levels: a gate must respond to levels greater than 2.0V (or input "1") or to levels less than 0.8V (or input "0"). Read full article