A system and method for processing product marketing rebate claims submitted by a consumer in satisfaction of a rebate offer, the consumer having purchased designated products in a qualified transaction recorded by a point-of-sale data processing and storage system that issues a receipt containing a corresponding transaction serial number. Bytes of data to be encoded having negative values are made positive while preserving the information to be encoded. Responsive to a flip signal received at an input node, the pulse generation circuit then transitions the output pulse from the relatively high state to the low state and sets the feedback node in a disable state. Further, when the handle is in the safety mechanism set position, the valve mechanism can always be kept in the valve closed state irrespective of air supply to the operation port. If the sensor is able to detect light from the light source, then the slides are properly loaded in the cassette.