|IC Number||IC Name|
|74LS04||Hex Inverting Gates|
|74LS08||Quad 2-input AND Gates|
|74LS32||Quad 2-input OR Gates|
|74LS86||Quad 2-input Exclusive-OR Gates|
Binary Coded Decimal (BCD) Code - Digital numbers are represented, stored and transmitted as group of binary bits. This group is also called as binary code decimals. Weighted binary codes are those binary codes which obey the positional weight principle. Each position of the number represents a specific weight. Several systems of the codes are used to express the decimal digits 0 through 9. In these codes each decimal digit is represented by a group of four bits.
In this code each decimal digit is represented by a 4-bit binary number. BCD is a way to express each of the decimal digits with a binary code. In the BCD, with four bits we can represent sixteen numbers (0000 to 1111). But in BCD code only first ten of these are used (0000 to 1001). The remaining six code combinations i.e. 1010 to 1111 are invalid in BCD.
Advantages of BCD Codes
Disadvantages of BCD Codes
Excess-3 Code - The Excess-3 code is also called as XS-3 code. It is non-weighted code used to express decimal numbers. The Excess-3 code words are derived from the 8421 BCD code words adding (0011)2 or (3)10 to each code word in 8421. The excess-3 codes are obtained as follows -
BCD to Excess-3 Code Converter - Excess-3 binary code is an unweighted self-complementary BCD code. Self-Complementary property means that the 1’s complement of an excess-3 number is the excess-3 code of the 9’s complement of the corresponding decimal number. This property is useful since a decimal number can be nines’ complemented (for subtraction) as easily as a binary number can be ones’ complemented; just by inverting all bits.
As is clear by the name, a BCD digit can be converted to it’s corresponding Excess-3 code by simply adding 3 to it.