Question 1

What type of logic circuit is represented by the figure shown below?

Accepted Answer

B

Question 2

What is the indication of a short to ground in the output of a driving gate?

Accepted Answer

B

Question 3

For the device shown here, assume the D input is LOW, both S inputs are LOW and the input is LOW. What is the status of the Y' outputs?

Accepted Answer

The D input is LOW, both S inputs are LOW, and the input is LOW. This means that the output will be LOW.

Question 4

Which of the following combinations of logic gates can decode binary 1101?

Accepted Answer

The answer of Which of the following combinations of logic...

Question 5

The carry propagation can be expressed as

Accepted Answer

Carry propagation in binary addition is expressed as the logical OR of the two bits, which is represented by a + b.

Question 6

3 bits full adder contains______________

Accepted Answer

The answer of 3 bits full adder contains______________
...

Question 7

The basic building blocks of the arithmetic unit in a digital computers are______________

Accepted Answer

Adders are the basic building blocks of the arithmetic unit in digital computers because they perform the fundamental operation of addition, upon which other arithmetic operations like subtraction, multiplication, and division can be constructed.

Question 8

A digital system consists of____________types of circuits.

Accepted Answer

Digital systems consist of two types of circuits: combinational and sequential.

Question 9

In a sequential circuit, the output at any time depends only on the input values at that time.

Accepted Answer

Sequential circuits' outputs depend on both past output (due to the memory elements in the circuit) and the present input values, distinguishing them from combinational circuits where the output depends only on the present input.

Question 10

The design of an ALU is based on______________

Accepted Answer

The ALU (Arithmetic Logic Unit) is a combinational logic circuit that performs arithmetic and logical operations on data. It is designed using combinational logic gates, such as AND, OR, XOR, and NOT gates, which are interconnected to implement the desired operations.

Question 11

If the two numbers are unsigned, the bit conditions of interest are the____________carry and a possible____________ result.

Accepted Answer

In unsigned arithmetic, the output carry is important as it indicates an overflow, and a zero result is significant as it indicates that the operation resulted in a zero value.

Question 12

If the two numbers include a sign bit in the highest order position, the bit conditions of interest are the sign of the result, a zero indication and______________

Accepted Answer

The correct answer is an overflow condition. When dealing with signed numbers, the conditions of interest include the sign of the result, a zero indication, and an overflow condition. Overflow occurs when the result of an arithmetic operation exceeds the range that can be represented with the given number of bits, including the sign bit.

Question 13

In parts of the processor, adders are used to calculate

Accepted Answer

Adders in a processor are versatile components used for various calculations, including computing addresses, table indices, and performing increment and decrement operations. These tasks are fundamental in processing and executing instructions, making adders crucial in the arithmetic logic unit (ALU) of a processor.

Question 14

Total number of inputs in a half adder is

Accepted Answer

A half adder has two inputs, typically represented as A and B, which are used to perform the addition of two single binary digits.

Question 15

In which operation carry is obtained?

Accepted Answer

The answer of In which operation carry is obtained?
...

Question 16

If A and B are the inputs of a half adder, the carry is given by______________

Accepted Answer

The carry output of a half adder is given by the AND operation of its two inputs, A and B. This is because a carry is generated only when both A and B are 1.

Question 17

Half-adders have a major limitation in that they cannot______________

Accepted Answer

Half-adders can add two single bits together but cannot process carry bits from previous stages, which is necessary for multi-bit addition. This limitation is addressed by full adders, which can handle carry input.

Question 18

If A, B and C are the inputs of a full adder then the carry is given by______________

Accepted Answer

The carry output of a full adder is given by the formula: (A AND B) OR ((A XOR B) AND C). This formula represents the conditions under which a carry is generated: either when both A and B are 1 (A AND B), or when one of A or B is 1 (A XOR B) and C is also 1. Choice A, "a and b or (a or b) and c," closely matches this logic, albeit with a slight misrepresentation in the use of "or" instead of "xor" for the (A XOR B) part. However, given the options, it's the closest to the correct logic for carry generation in a full adder.

Question 19

How many AND, OR and EXOR gates are required for the configuration of full adder?

Accepted Answer

A full adder can be implemented with 2 AND gates, 1 OR gate, and 2 EXOR gates. This configuration allows for the addition of three bits (two input bits and a carry bit) with the correct output of sum and carry.

Question 20

How many outputs are required for the implementation of a subtractor?

Accepted Answer

A subtractor requires two outputs: the difference and the borrow.

Quiz 4: Logic Circuit and Arithmetic Unit