In a circuit involving integrated circuits, the documentation for the ic often states that if a pin is in logic 1 or high the circuit will behave in one way, and if the circuit is in logic 0 or low the circuit will behave in another way. One example i found was experimenting with the 4029 CMOS Counter ic http://www.intersil.com/content/dam/Intersil/documents/fn33/fn3304.pdf on the up/down and dec/bin pins. What i don't understand, is what the pin that is set either high or low should be connected to i would assume it would be the positive supply voltage, the negative supply voltage, or neither, but i can't seem to figure out which one.
Answer
The bottom of page 7-799 of the linked datasheet gives the thresholds for low and high input voltages given a couple of different supply voltages. As long as the voltage on the input is at most/least that value when referenced to ground the input is considered low/high regardless of what you tie it to.
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