The 6049 is a four-channel input module for use with quadrature encoders. Each channel has optical isolation for the "A", "B", and "Z" inputs. The "A" and "B" quadrature inputs feed a 32 bit up/down accumulator, that may be set or cleared under program control. The up/down polarity for each 32 bit accumulator is programmable. A short debounce filter for the "A", "B", and "Z" inputs can be programmed for 0 to 230 nsec.