The product described herein is a TTL compatible dual high speed circuit intended for sensing in a broad range of system applications. While the primary usage will be for line receivers of MOS sensing, the product may effectively be used as a voltage comparator, level translator, window detector, transducer preamplifier, and in other sensing applications. As a digital line receiver the product is applicable with the SN55109/SN75109 and A75110/DS75110 companion drivers, or may be used in other balanced or unbalanced party-line data transmission systems. Input protection diodes are incorporated in series with the collectors of the differential input stage. These diodes are useful in certain applications that have multiple VCC+ supplies or VCC+ supplies that are turned off.