Digital logic uses the boolean logic represented with high and low voltage values: depending on what voltage represents the /true/ value the logic is active high or active low.
With technology improvement the voltage ranges used to represent logic level has changed
|Technology||L Voltage||H Voltage||Notes|
|CMOS||0V to 1/3VDD||2/3 Vdd to Vdd||Vdd = supply voltage|
|TTL||0V to 0.8V||2V to Vcc||Vcc = 5 +/- 10%|
- Tri-state logic: Connecting multiple outputs together - 8 bit register - Part 2 video
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