Abstract: We have designed and built a microcomputer γ spectrum system The systemconsists of a 80 cm~3 HPGe detector, a 8192 ADC, a 8 kB 24 Bit buffer memory,a CRT display, a TRS--80Ⅲ microcomputer and a variety of software. The systemresolution is 2.35 keV at 1.33 MeV. The system stability is less than 0.02％ at8 hours.