The Ids-V(g) characteristics of the aluminum-oxide glassy alloy (Ni(0.36)Nb(0.24)Zr(0.40))(90-)H(10) field-effect transistor (GAFET) for gate-drain bias voltage from -50 to +50 mu V were measured at room temperature. We observed four kinds of drain current oscillations for gate voltage at two-current plateau regions of -20 similar to -15 and +35 similar to +40 mu V. The transistor showed the three-dimensional Coulomb diamond structure. From DC current standards I = ef, we get f = 256 GHz for the first peak, being tunneling of one electron.