The CD4063B is a 4-bit magnitude comparator designed for use in computer and logic applications that require the comparison of two 4-bit words. This logic circuit determines whether one 4-bit word (Binary or BCD) is "less than", "equal to", or "greater than" a second 4-bit word.

The CD4063B has eight comparing inputs (A3, B3, through A0, B0), three outputs (A B) and three cascading inputs (A B) that permit systems designers to expand the comparator function to 8, 12, 16 . . . 4N bits. When a single CD4063B is used, the cascading inputs are connected as follows: (A B) = low.

For words longer than 4 bits, CD4063B devices may be cascaded by connecting the outputs of the less-significant comparator to the corresponding cascading inputs of the more-significant comparator. Cascading inputs (A B) on the least significant comparator are connected to a low, a high, and a low level, respectively.