## Pull-up Resistors

Digital logic gates can be used for connection to external circuits or devices but care must be taken to ensure that their inputs or outputs function correctly and provide the expected switching condition. Modern digital logic gates, IC’s and micro-controllers contain many inputs, called “pins” as well as one or…

## Universal Logic Gates

Individual logic gates can be connected together to form a variety of different switching functions and combinational logic circuits. As we have seen throught this Digital Logic tutorial section, the three most basic logic gates are the: AND, OR and NOT gates, and given this set of logic gates it is possible to implement all of the…

## Digital Logic Gates Summary

We have also seen that each gate has an opposite or complementary form of itself in the form of the NAND Gate, the NOR Gate and the Buffer respectively, and that any of these individual gates can be connected together to form more complex Combinational Logic circuits. We have also seen, that…

## Digital Buffer Tutorial

In a previous tutorial we looked at the digital Not Gate commonly called an inverter, and we saw that the NOT gates output state is the complement, opposite or inverse of its input signal. So for example, when the single input to NOT gate is “HIGH”, its output state will NOT be…

## Exclusive-NOR Gate Tutorial

Basically the “Exclusive-NOR” gate is a combination of the Exclusive-OR gate and the NOT gate but has a truth table similar to the standard NOR gate in that it has an output that is normally at logic level “1” and goes “LOW” to logic level “0” when ANY of its inputs are…

## Exclusive-OR Gate Tutorial

In the previous tutorials, we saw that by using the three principal gates, the AND Gate, the OR Gate and the NOT Gate, we can build many other types of logic gate functions, such as a NAND Gate and a NOR Gate or any other type of digital logic function…

## Logic NOR Gate Tutorial

The inclusive NOR (Not-OR) gate has an output that is normally at logic level “1” and only goes “LOW” to logic level “0” when ANY of its inputs are at logic level “1”. The Logic NOR Gate is the reverse or “Complementary” form of the inclusive OR gate we have seen previously. Logic NOR…

## Logic NOT Gate Tutorial

Inverting NOT gates are single input devicse which have an output level that is normally at logic level “1” and goes “LOW” to a logic level “0” when its single input is at logic level “1”, in other words it “inverts” (complements) its input signal. The output from a NOT…

## Logic NAND Gate Tutorial

The NAND (Not – AND) gate has an output that is normally at logic level “1” and only goes “LOW” to logic level “0” when ALL of its inputs are at logic level “1”. The Logic NAND Gate is the reverse or “Complementary” form of the AND gate we have seen previously. Logic NAND Gate Equivalence The logic…

## Digital Logic Gates

Digital logic gates can have more than one input, for example, inputs A, B, C, D etc., but generally only have one digital output, (Q). Individual logic gates can be connected or cascaded together to form a logic gate function with any desired number of inputs, or to form combinational…

## Logic OR Gate Tutorial

The output, Q of a “Logic OR Gate” only returns “LOW” again when ALL of its inputs are at a logic level “0”. In other words for a logic OR gate, any “HIGH” input will give a “HIGH”, logic level “1” output. The logic or Boolean expression given for a digital logic…

## Logic AND Gate Tutorial

The output state of a digital logic AND gate only returns “LOW” again when ANY of its inputs are at a logic level “0”. In other words for a logic AND gate, any LOW input will give a LOW output. The logic or Boolean expression given for a digital logic AND gate…