Binary Coded Decimal BCD conversions
Binary Coded Decimal BCD conversions
BCD (Binary Coded Decimal)
� It represents 0 to 9 digits.
� 4-bits binary = 1-bit BCD.
� Invalid BCD numbers are 1010, 1011, 1100, 1101, 1110 and 1111.
Decimal Digit BCD
0 1 2 3 4 5 6 7 8 9 (decimal number)
0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 (BCD code)
Convert BCD code into Decimal number
(10000110)2
Step 1: break the given number in 4, 4-bit.
1000 0110
Step 2: convert these 4-bit into their respective decimal numbers.
1000 0110
8 6
Given BCD is (86)10 in Decimal number.
Convert Decimal number into BCD code
(453)10
Step 1: convert each decimal digit into 4-bit of binary number.
4 5 3
0100 0101 0011
Step 2: join these binary digits.
(010001010011)2
BCD Addition
23 ? 00100011
+15 ? 00010101
38 ? 00111000
BCD Subtraction
86-41=?
41 ? 01000001 ? 2�s compliment ? 10111111 ? -41
86 ? 10000110
-41 ? 10111111
45 ? 1 01000101
Here left most 1 is discarded.
Note:
If answer of addition or subtraction of BCD numbers is invalid, then add +6 or -6 respectively to their answers to get valid answer.
