# 15 Lecture

## CS302

### Midterm & Final Term Short Notes

## BCD ADDER

A BCD adder is a combinational logic circuit that adds two Binary Coded Decimal (BCD) numbers and produces a BCD output. BCD is a system of representing numbers in which each digit is represented by a binary code. BCD adder circuits are used in

**Important Mcq's**

Midterm & Finalterm Prepration

Past papers included

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**What is the purpose of a BCD adder circuit?**A) To add two binary numbers B) To add two decimal numbers C) To add two BCD numbers D) To subtract two BCD numbers

Answer: C

**Which type of logic gates are used in BCD adder circuit?**A) AND gates B) OR gates C) XOR gates D) All of the above

Answer: D

**How many bits are required to represent a single BCD digit?**A) 2 B) 3 C) 4 D) 5

Answer: C

**How many full adders are required to design a 4-bit BCD adder?**A) 1 B) 2 C) 3 D) 4

Answer: 2

**Which input(s) of a BCD adder are applied to the carry-in of the first full adder?**A) The least significant bit (LSB) of both inputs B) The most significant bit (MSB) of both inputs C) The carry-out of the previous stage and the LSB of the current stage input D) None of the above

Answer: D

**What is the maximum sum that can be generated by a single BCD adder?**A) 9 B) 10 C) 15 D) 16

Answer: 9

**What is the carry-out of a full adder when both inputs are 1?**A) 0 B) 1 C) 2 D) Cannot be determined

Answer: 1

**Which type of multiplexer is used in BCD adder to select between the carry-in and sum output of the full adder?**A) 2:1 B) 4:1 C) 8:1 D) 16:1

Answer: A

**What is the purpose of the parity generator in BCD adder circuit?**A) To check for errors in the input data B) To ensure that the output is a valid BCD number C) To generate a parity bit for error detection D) None of the above

Answer: B

**What is the maximum number of BCD digits that can be added using an 8-bit BCD adder?**A) 1 B) 2 C) 4 D) 8

Answer: 2

**Subjective Short Notes**

Midterm & Finalterm Prepration

Past papers included

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**What is BCD code?**BCD stands for Binary Coded Decimal which is a coding scheme used to represent decimal numbers in binary form.**What is the purpose of BCD adder circuit?**The purpose of a BCD adder circuit is to add two BCD numbers and provide the output in BCD format.**How many digits can a BCD adder circuit handle?**A BCD adder circuit can handle up to four digits in each BCD number.**What is the significance of carry propagation in BCD adder?**Carry propagation is important in BCD adder as it carries the carry from one digit to the next when the sum of two digits exceeds nine.**What is the difference between a BCD adder and a binary adder?**A BCD adder operates on binary coded decimal numbers, while a binary adder operates on binary numbers.**What is a half adder?**A half adder is a combinational circuit that adds two single-bit binary numbers and produces a sum and carry bit as output.**What is a full adder?**A full adder is a combinational circuit that adds three single-bit binary numbers and produces a sum and carry bit as output.**What is the difference between a half adder and a full adder?**A half adder can only add two single-bit binary numbers, while a full adder can add three single-bit binary numbers.**What is ripple carry adder?**A ripple carry adder is a type of adder circuit where the carry output from each stage is fed as an input to the next stage.**What is carry lookahead adder?**A carry lookahead adder is a type of adder circuit that uses lookahead logic to calculate carry bits, resulting in faster operation than a ripple carry adder.