The HCTL-2xx1(7)-A00/PLC is CMOS ICs that performs the quadrature decoder, counter, and bus interface function. The HCTL-2xx1(7)-A00/PLC is designed to improve system performance in digital closed loop motion control systems and digital data input systems. It does this by shifting time intensive quadrature decoder functions to a cost effective hardware solution. The HCTL-2xx1(7)-A00/PLC consists of a quadrature decoder logic, a binary up/down state counter, and an 8-bit bus interface. The use of Schmitt-triggered CMOS inputs and input noise filters allows reliable operation in noisy environments. The HCTL-2001-A00 contains 12-bit counter and HCTL-2017-A00/PLC or HCTL-2021A00/PLC contains 16-bit counter and provides TLL/ CMOS compatible tri-state output buffers. Operation is specified for a temperature range from 40 to +85C at clock frequencies up to 14MHz.