# Important Questions of Binary Codes

In this post, some of the important questions of binary codes are given. It includes different types of binary codes, meaning of alphanumeric code and numeric code, meaning of BCD code, code word meaning, different types of BCD code, weighted code and non-weighted code, positive weighted code and negative weighted code, sequential code, self-complementing code, cyclic code, unit distant code, application of cyclic code, 8421 BCD code

, natural binary code, difference between BCD code and natural BCD code, illegal 8421 BCD code, Excess 3 code and invalid states of Excess 3 code.

## Types of Binary Codes

### What are the different types of binary codes

Types of binary codes

• Numeric codes
• Alphanumeric codes

### What is meant by alphanumeric code and numeric code?

Alphanumeric code

• The alphanumeric code represents letters of alphabet and decimal numbers

Numeric code

• The numeric code represents only numeric number i.e. 0s and 1s

### What is meant by BCD code?

BCD code

• The full form of BCD is binary coded decimal.
• When numeric codes used to represent decimal digits are called as binary coded decimal codes.

### Explain the term : Code word

Code word

• It is a sequence of binary digits which represents a decimal digit.

## Types of BCD Codes

### Describe the different types of BCD code.

BCD code

• Weighted code : ( 1 ) Positive weighted code and ( 2 ) Negative weighted code
• Non – weighted code

## Weighted code and Non-Weighted Code

### What is meant by weighted code and non – weighted code?

Weighted code

• It is code in which each position of number has specific weight.

Non – weighted code

• It is code in which each position of number does not obey weighted position principle.

### What is meant by positive weighted code and negative weighted code?

Positive weighted code

• It is code in which all the weights assigned to the binary digits are positive. The first weight must be 1 in all positive weighted code.
• The 4311, 3321 and 5211 are some of examples of positive weighted code.

Negative weighted code

• It is a code in which at least one of the weights assigned to the binary digit is negative.
• The 642-3 and 84-2-1 is example of negative weighted code.

## Sequential code

### What is meant by sequential code?

Sequential code

• It is code in which each succeeding code word is one binary number greater than the preceding code word.
• The 8421 and XS – 3 code are example of sequential code.

### Describe the condition for self-complementing code.

The given code is self-complementing if the sum of the all weights of number is equal to 9. The 2421, 5211, 642 – 3, 84 – 2 – 1 are example of self-complementing codes.

## Cyclic Code

### What is cyclic code?

Cyclic code

• It is code in which each successive code word differs from the preceding one in only one bit position.

### Which code is called as unit distant code? Give example

Cyclic code

• The cyclic code is called as unit distant code because each successive code word differs from the preceding one in only one bit position.
• The Grey code is cyclic code.

### Write one application of cyclic code

The cyclic code is used to translating an analog quantity of shaft position into digital quantity.

### Why the Gray code is also called as cyclic code?

Gray code

• The Gray code is also called as cyclic code because successive code words in this code differ in one bit position only.

### Why the 8421 BCD code is also called as naturally binary code?

8421 BCD code

• The 8421 BCD code is also called as naturally binary code because 8,4, 2 and 1 weight is attached to it.

### Describe the disadvantages of 8421 BCD code over binary code.

Disadvantages of 8421 BCD code over binary code

• It require more bits as compared to that of binary code
• The binary addition and subtraction rules do not apply to the 8421 number but it is applicable only for group of 4 bits.

### Describe the advantages of 8421 BCD code over binary code.

Advantages of 8421 BCD code over binary code

• Ease of conversion in decimal number and vice versa

### Describe the main difference between BCD code and 8421 BCD code.

8421 BCD code

• The 8421 BCD code is simply as BCD code but each decimal digit is coded by 4 digit binary numbers in it.

### Which are the illegal 8421 BCD codes? Why?

There are 1010, 1011, 1100, 1101, 1110 and 1111 are illegal code because some of all weight of each code is greater than 9.

• 1010 = 8 + 0 + 2 + 0 = 10
• 1011 = 8 + 0 + 2 + 1 = 11
• 1100 = 8 + 4 + 0 + 0 = 12
• 1101 = 8 + 4 + 0 + 1 = 13
• 1110 = 8 + 4 + 2 + 0 = 14
• 1111 = 8 + 4 + 2 + 1 = 15

### How the Excess 3 code is derives?

The Excess 3 code is derived by addition of three 0011 to 8421 BCD code.

### Which are the invalid states in the Excess 3 code? Why?

There are following invalid state in the Excess 3 code because some of its weight is less than three or greater than 13

• 0000 = 0 + 0 + 0 + 0 = 0
• 0001 = 0 + 0 + 0 + 1 = 1
• 0010 = 0 + 0 + 1 + 0 = 2
• 1101 = 8 + 4 + 0 + 1 = 13
• 1110 = 8 + 4 + 2 + 0 = 14
• 1111 = 8 + 4 + 2 + 1 = 15