Real-time (life) testing of the soft-error rate (SER) is an experimental reliability technique to determine the soft error sensitivity of a given component, circuit or system from the monitoring of a population of devices subjected to natural radiation and operating under nominal conditions. We present here a survey of real-time testing results accumulated from 2006 at mountain altitude on the Altitude SEE Test European Platform (ASTEP) and underground at the Underground Laboratory of Modane (LSM). Radiation data concern three generations of SRAMs manufactured in CMOS 130, 65 and 40 nm technologies.