HEF4585B

The HEF4585B is a 4-bit magnitude comparator which compares two 4-bit words (A and B), whether they are 'less than', 'equal to', or 'greater than'. Each word has four parallel inputs (A₀ to A₃ and B0 to B3); A3 and B3 being the most significant inputs. Three outputs are provided;A greater than B (O_A > B), A less than B (O_A < B) and A equal to B (O_A = B). Three expander inputs (I_A > B, I_A < B and I_A = B) allow cascading of the HEF4585B without external gates.

For proper compare operation the expander inputs to the least significant position must be connected as follows:I_A = B = I_A > B = HIGH, IA < B = LOW. For words greater than 4-bits, HEF4585B units can be cascaded by connecting outputs O_A < B and O_A = B to the corresponding inputs of the next significant comparator (input I_A > B is connected to a HIGH).

Operation is not restricted to binary codes, the devices will work with any monotonic code. The function table of HEF4585B describes the operation of the device under all possible logic conditions.