Abstract: An improved diagnosis test apparatus and test method for a small computer system interface (SCSI) that are capable of controlling the input/output of SCSI test data and SCSI signal data which are generated by a host computer without using a peripheral SCSI device. The apparatus includes a host computer for inputting/outputting SCSI control data and SCSI test data, and a controller for receiving and temporarily storing the SCSI control data and SCSI test data from the host computer and for outputting the data to the host computer, for thus testing the SCSI.

Abstract: An oscillation circuit employs a piezo-electric crystal connected in parallel with an amplifier having a gain equal to or less than that needed to maintain a steady-state operation of the amplifier when operated at the maximum output. One or more controllable amplifiers are connected in parallel with the amplifier and controlled according to the level of the oscillation signal, to rapidly amplify an initial oscillation to steady-state operation level and to keep it there without exceeding the output level of the crystal while minimizing the energy supplied to the entire oscillation circuit.