4-4) Principles of Logic Gates

Question 1

What are the 3 most basic logic gates?

Answer 1

Inverter, AND, OR

Question 2

What are 5 basic types of logic gates that can be produced using the 3 most basic logic gates?

Answer 2

Inverter, AND, OR, NAND, NOR

Question 3

Draw the symbol for an inverter gate.

Answer 3

Question 4

Draw the symbol for an AND gate.

Answer 4

Question 5

Draw the symbol for an OR gate.

Answer 5

Question 6

Draw the symbol for a NAND gate.

Answer 6

Question 7

Draw the symbol for a NOR gate.

Answer 7

Question 8

Draw the symbol for a XOR gate.

Answer 8

Question 9

Draw the symbol for an XNOR gate.

Answer 9

Question 10

What is a logic gate?

Answer 10

A logic gate is a device with only one output and two or more inputs. Logic gates represent the basic building blocks of digital circuits and represent decision making required in electronic circuits.

Question 11

What are some components that may represent logic gates in an electronic circuit?

Answer 11

transistors, lights, diodes

Question 12

What is a logic level?

Answer 12

A voltage of a specified value that is used to represent either a binary “1” or “0.” “On” or “Off.” “High” or “Low.”

Question 13

What is a logic symbol?

Answer 13

A log symbol is a pictorial representation of a logic function. A symbol does not indicate any particular components but does indicate the function.

Question 14

What is logic high?

Answer 14

The most positive of two voltage levels.

Question 15

What is logic low?

Answer 15

The most negative of two voltage levels.

Question 16

What is logic low?

Answer 16

The most negative of two voltage levels.

Question 17

What is a logic function?

Answer 17

A function expressing a relationship between variable input(s) to a system device and the resultant output.

Question 18

What is a gate?

Answer 18

A device that has two or more inputs and only one output.

Question 19

What is a truth table?

Answer 19

A table that shows all possible input combinations to a logic function and the resultant outputs.

Question 20

What are the rules for an AND gate?

Answer 20

• All inputs must be high to product high output
• Only ONE combination will produce a high output
• And low input = low output

Question 21

Write out an AND gate truth table.

Answer 21

Question 22

How do AND gate rules change when you had more than 2 inputs?

Answer 22

They don’t. The same rules apply. All inputs must be high before a high can be produced. A good example is a pilot’s checklist where all items on the checklist need to be “high” before the aircraft can fly.

Question 23

What are the rules for an OR logic gate?

Answer 23

• If any inputs are high, the output is high.

Question 24

Write out an OR gate truth table.

Answer 24

Question 25

What are the rules for a NAND gate?

Answer 25

* A NAND gate is similar to the AND gate except it adds an inverter at the end. * Also known as a Not AND gate. * Logic gate inputs are the same as the AND gate, but the outputs are opposite, inverted * All high inputs will produce a low output * Any low input will cause a high output

Question 26

Write out a NAND gate truth table.

Answer 26

????? AET Volume 2 56-57?

Question 27

Explain how to use an Inhibitor Gate

Answer 27

?????

Question 28

What are the rules for a NOR gate?

Answer 28

* If any input is high, the output is low * If all inputs are low, the output will be high

Question 29

Write out a NOR gate truth table

Answer 29

Question 30

What are the rules for an XNOR gate?

Answer 30

* This is an XOR gate with an inverted output. * It produces a HIGH output when the inputs are either all HIGH or all LOW.

Question 31

Write out a truth table for an XNOR gate.

Answer 31

Question 32

What are the rules for a XOR gate?

Answer 32

* XOR gate is a modified OR gate that produces a HIGH output when one and only one of the inputs is HIGH. * When both inputs are HIGH or when both inputs are LOW, the output in LOW.

Question 33

Write out a truth table for a XOR gate.

Answer 33

Question 34

What is a buffer gate?

Answer 34

Buffers do not invert the signal like a NOT gate. Buffers are connection devices that connect circuits together. This could be for isolation, protection, filtering, distribution or impedance matching.

Question 35

What is an inverter?

Answer 35

An inverter inverts a single input signal. 0 becomes 1, 1 becomes 0. Output is 180° out of phase from the input.

Question 36

How do you recognize an inverter or NOT gate from annotation?

Answer 36

Output may be labeled with a vinculum ( — ) Ā on the output (if the input is “A”). A small bubble _^o may also be located on the input or output side.

Question 37

Review timing charts for logic gates and compare with truth tables.

Question 38

What are flip-flops?

Answer 38

Flip-flops are synchronous bistable storage devices capable of storing one bit. The output changes are synchronized with a clock signal.

Question 39

What is the difference between latches and flip-flops?

Answer 39

The main difference between latches and flip-flops is the method used to change their states. Latches are **level sensitive**, or level-triggered. This means that the outputs are dependent on the voltage level applied, not on any signal transition. Flip-flops are edge-triggered, that is that they depend on the transition of a signal. They may either be a LOW-to-HIGH (rising edge) or a HIGH-to-LOW (falling edge) transition.

Question 40

When using logic symbols, what annotation is used to show edge triggering?

Answer 40

A small triangle inside the block at the clock input (C). The absence or presence of a bubble, outside the block, is used to indicate rising and falling edge triggering respectively.

Question 41

What do S and R stand for in S-R flip-flop?

Answer 41

S and R stand for Set and Reset.

Question 42

What is an S-R Flip-Flop?

Answer 42

This is a trigger that sets the Flip-Flop state from either 1 or 0. S and R inputs determine what happens to the flip-flop and the clock determines when it happens.

Question 43

What is a D flip-flop?

Answer 43

AET volume 2 page 65--shitty explanation

Question 44

What is a J-K Flip-Flop?

Answer 44

The J-K flip flop is perhaps the most widely used type of flip-flop. Its function is identical to the S-R flip-flop in the SET, RESET and HOLD conditions of operation. The difference is that the J-K flip-flop does not have any invalid states.

Question 45

Explain the difference and application of S-R, D and J-K Flip-Flops.

Answer 45

No idea… maybe AET Volume 2 Page 66, shitty explanations.

Question 46

Explain how counters work.

Answer 46

No idea… AET volume 2 page 67-69

Question 47

Explain how logic adders work.

Answer 47

No idea…

Question 48

Explain how logic half adders work.

Answer 48

No idea

Question 49

Explain how full adders work.

Answer 49

No idea