| Integers: BCD | |||||||||||||
| Since people think in decimal, it may be convenient to use a decimal-like representation. | |||||||||||||
| Binary coded decimal (BCD) uses unsigned binary to represent each decimal digit. | |||||||||||||
| How many bits are needed? | |||||||||||||
| 4 bits per decimal digit: ceil (lg 10) = 4 | |||||||||||||
| Since 4 bits can represent 16 values, 6 values are unused for every digit. | |||||||||||||
| Advantages | |||||||||||||
| Decimal input/output doesn't require complicated conversion. | |||||||||||||
| Fewer problems with repeating fractions. | |||||||||||||
| Example: | |||||||||||||
| Represent 1739ten in BCD: | |||||||||||||
| decimal | 1 | 7 | 3 | 9 | |||||||||
| BCD | 0001 | 0111 | 0011 | 1001 | |||||||||