An Intel 8080 microprocessor is used to control the running, and also analyse the results of a clinical test, the electrooculogram. The processor provides a moving stimulus using a strip of thirty-two light emitting diodes. From electrodes attached medial and lateral to the eyes, the sinusoidal signals generated by the stimulated lateral eye movements are monitored, digitised by the processor and the peak values stored for subsequent analysis. Results are plotted both numerically and graphically each minute of the test on a standard teletype. Throughout the test, systems faults are recognised and appropriate error messages produced. The test is automatically terminated and results calculated when sufficient data has been collected. The development of this system and the advantages of a microprocessor in this application are discussed.