Q.Distinguish between excess-3 and BCD codes.

BCD (8421) code represents each decimal digit by its natural 4-bit binary equivalent and is a weighted code, whereas excess-3 code is formed by adding 3 (binary 0011) to the BCD code and is a non-weighted, self-complementing code. …

[!TLDR]

BCD (8421) is a weighted code equal to the digit's binary value; excess-3 is a non-weighted, self-complementing code equal to BCD + 3.

Both codes represent a single decimal digit using four bits, but they differ in construction and properties.

BCD (Binary Coded Decimal, 8421): each decimal digit 0-9 is written as its plain 4-bit binary number, with position weights 8, 4, 2, 1. It is therefore a weighted code, and the value of a code word can be found by adding the weights of the 1-bits. …