A system for measuring output characteristics of FET's using nanosecond pulses, instead of dc voltage and current measurement, is described. The measurement system is used to obtain the I-V characteristics of silicon-on-insulator (SOI) FET's without the degradation resulting from self heating. Use of the technique to study partially depleted SOI FET's with floating bodies shows that under pulsed conditions, their output curves have a history dependence. The physical mechanisms responsible for the history dependence are explained. Further understanding of the physical mechanisms is given by examination of single-shot pulse measurements. The role of transient and time-dependent phenomena in determining I-V curves is elucidated.