Q10: Universal Gates
Time Estimate15-30 minutes Grade Impact0.5% DueSep 21 @ 12pm
Objective
Reinforce an understanding of NAND and NOR universal logic gates.
Additional Materials & Formats
Check Box for the most up-to-date versions of this lecture’s materials.
Free Response Questions
-
What does it mean for a logic gate to be universal, and why are NAND and NOR considered universal gates?
-
What is the advantage of using universal gates in digital circuit design, and how does this impact the manufacturing process?
-
Why might an engineer choose to use NAND gates over NOR gates, or vice versa, in a specific application?
Multiple Choice Questions
-
A NAND gate produces an output of 0 only when:
- at least one input is 0
- both inputs are 0
- all inputs are 1
- the inputs are different
-
What is the Boolean expression for the NAND gate output?
- $Y = A \land B$
- $Y = \lnot (A \land B)$
- $Y = (A \lor B)'$
- $Y = \lnot A \land \lnot B$
-
Which construction correctly creates a NOT gate using only NAND gates?
- Connect the two NAND inputs together
- Connect two NAND gates in series
- Feed the output of one NAND gate into an OR gate
- Tie both outputs together
-
Which statement best describes NOR gates?
- NOR outputs 1 when at least one input is 1
- NOR is the complement of AND
- NOR outputs 1 only when all inputs are 0
- NOR cannot be used to build other gates
-
What is the best explanation for why NAND gates are commonly used in practice?
- They are less expensive and easier to implement in CMOS technology
- They can only implement OR functions
- They are universal, but NOR is not
- They always produce a 0 output
-
How can an AND gate be built using only NOR gates?
- Use one NOR gate with both inputs connected together
- Invert both inputs with NOR gates, then feed them into a third NOR gate
- Use two NOR gates in series with no inversion
- Use a NAND gate followed by a NOR gate
-
Which pair of gates is universal?
- AND and OR
- XOR and NOT
- NAND and NOR
- NOT and OR