A 10-channel counter-timer circuit designed to monitor the rates of particle detectors is presented. It utilises two Am9513 'System Timing Controller' chips together with ancillary logic and is compatible with the IEEE-Std-696/S-100 computer bus. Input signals of up to 6.9 MHz on 10 twisted-pair lines can be counted with 16-bit accuracy. Alternatively, the circuit can be reconfigured by software to form two 80-bit counters. It is also capable of a wide range of time interval measurements, sequencing and digital waveform generation.