A pattern matching unit includes a selection unit to divide an input datum and one or more reference templates into input bit-fields corresponding reference bit-fields, respectively. The number of bits in the input and reference bit-fields is programmable. A distance unit is also included to determine one or more distance measures between the input bit-fields and the corresponding reference bit-fields. The distance measures associated with reference bit-fields are combined into one or more net distance measures corresponding to the one or more reference templates.