The authors developed a computerized electroencephalography with a IBM PC AT. EEG signals amplified with 16 channels (Nihon Kohden EEG-4313 F) were acquired through a DTX 2806 and a DTX 311 (Data Translation) into a computer. EEG activity was digitized at 102.4 Hz(1024 samples per epoch). Shifted DC potentials and 60 Hz artifact were removed by high pass filter and 60 Hz notch filter. A window function consisting of a 10% cosine taper was obtained by weighing the points at either end of the epoch by a cosine bell. A fast Fourier transform was applied to every epoch and the power spectrum estimates computer at 0.39 Hz steps. For smoothing, adjacent estimates were summed to yield 1-Hz resolution, with the final estimates expressed as magnitude values in microvolts(square root of power). The activity estimates for the delta, theta, alpha and beta bands were computed by summing adjacent values * delta 0.7-4.3，theta 4.7-7.8, alpha 8.2-12.9，betal 13.9-19.9, beta2 20.3-31.6. The function of the system was tested using with 10 Hz sine wave from a functional generator and a human EEG.

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