ECS 154A Discussion Section 10/17
BCD (Binary-Coded Decimal)
• 4-bit binary
• total: 10 decimal digits (0 to 9) in binary number
• includes 0000 – 1001, excludes 1010 – 1111
Number Representation
Decimal BCD
0 0000
1 0001
2 0010
3 0011
4 0100
5 0101
6 0110
7 0111
8 1000
9 1001
Addition
• Example 1:
2 = 0010
3 = 0011
0101 = 5
• Example 2:
7 = 0111
2 = 0010
1001 = 9
• Example 3:
6 = 0110
2 = 0010
1000 = 8
• Example 4:
8 = 1000
9 = 1001
1 0001
Error: 1 0001 in BCD is 11 in decimal, result should be 0001 0111 in BCD
Therefore,
If the digit sum > 9, add 6 (0110)
