ffect. Geminate and columnar recombination lead to reduced charge yield, per unit rad, in proton environments. Even so, the assumption of a linear superposition of electron and proton dose, combined with Co-60 or 10 keV x-ray testing for component evaluations leads to reasonable estimates which may be slightly conservative in proton dominated dose environments. In closing, we would like to remind the reader that these comments address the fidelity of response estimated for proton-induced total ionizing dose only. If displacement effects are important, then there is no substitute for carefully planned tests, and x-ray or gamma ray testing is probably not appropriate. More will be made of this point in the section IVB on displacement effects. 4.0 PROTON-INDUCED SINGLE EVENT EFFECTS The basis for the classic approach to single event effects from protons first appeared in [Guen-79]. Here, the upset mechanism description involved the proton (or neutron) initiating an inelastic nuclear reaction leading to high energy recoil atoms and subsequent localized ionization sufficient to cause upset. Proton upset in satellite microelectronics was not a major concern at first because of the larger feature sizes and correspondingly high critical charge required for upset. In time this would change, and within a few years, missions routinely saw upset rate increases corresponding to high proton fluxes. In the 1995 NSREC Short Course IV-22 segment on "Single Event Effects Qualification," Bill Stapor includes a list of 30 missions with confirmed proton-induced SEE experiences. Today, that list would be much longer. In 1984 the key paper appeared, "Predicting Single Event Upsets in the Earth's Proton Belts" [Bend-84]. This semi-empirical model assumes the proton reaction based mechanism and allows the use of SEE test data at a single proton energy or multiple energies for the prediction of upset rates in the proton belts. In the single parameter model, the parameter relates the proton upset sensitivity to the proton energy threshold 