ALU 101 Adder Circuits and Addition Logic

Question 1

What are the two outputs produced by a half adder?

Accepted Answer

Sum and Carry

Answer

Sum and Borrow

Answer

Product and Carry

Answer

Quotient and Remainder

Question 2

How many inputs does a full adder have?

Accepted Answer

3

Answer

2

Answer

4

Answer

5

Question 3

Which logic gate implements the Sum output of a half adder?

Accepted Answer

XOR gate

Answer

AND gate

Answer

OR gate

Answer

NAND gate

Question 4

What is the correct Boolean expression for the carry-out of a full adder?

Accepted Answer

(A AND B) OR (Cin AND (A XOR B))

Answer

A XOR B XOR Cin

Answer

A AND B AND Cin

Answer

A OR B OR Cin

Question 5

In a ripple carry adder, how does the carry signal travel through the circuit?

Accepted Answer

The carry output of each stage feeds into the carry input of the next stage

Answer

All carries are computed simultaneously in parallel

Answer

Carries are stored in registers between clock cycles

Answer

Carries are discarded and recomputed at each stage

Question 6

What is the primary disadvantage of a ripple carry adder?

Accepted Answer

Propagation delay grows linearly with word length

Answer

High static power consumption

Answer

It cannot add unsigned numbers

Answer

It requires more hardware than a carry lookahead adder

Question 7

How many full adders are required to build a 4-bit ripple carry adder?

Accepted Answer

4

Answer

2

Answer

3

Answer

8