A new preprocessor for the University of Washington modified SP-3000 positron emission tomograph was designed and built. The device improves the maximum coincidence counting rate of the machine to greater than 450000 events per second in preprocessed mode. The new hardware also improves image quality by implementing time-of-flight offset corrections by crystal pairs, position and time-of-flight gating for the rotating sector source (for attenuation scans), and supporting corrections of randoms based on estimating singles rates from rejected time-of-flight events. The improved hardware can be installed on any SP-3000 series tomograph with modest modifications to calibration and data acquisition software.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>