2.13 Binary-Coded Decimal Representation
Although the integer and floating-point formats cover most of the numeric needs of an average program, there are some special cases where other numeric representations are convenient. In this section we'll discuss the binary-coded decimal format because the 80x86 CPU provides a small amount of hardware support for this data representation.
BCD values are a sequence of nibbles, with each nibble representing a value in the range 0..9. Of course you can represent values in the range 0..15 using a nibble; the BCD format, however, uses only 10 of the possible 16 different values for each nibble.
Each nibble in a BCD value represents a single decimal digit. Therefore, with a single byte (i.e., two digits) we can ...
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