Soft Errors in Combinational Logic
The three natural masking effects in combinational logic that determine whether a single event upset (SEU) will propagate to become a soft error are electrical masking, logical masking, and temporal (or timing-window) masking. An SEU is logically masked if its propagation is blocked from reaching an output latch because off-path gate inputs prevent a logical transition of that gate's output. An SEU is electrically masked if the signal is attenuated by the electrical properties of gates on its propagation path such that the resulting pulse is of insufficient magnitude to be reliably latched. An SEU is temporally masked if the erroneous pulse reaches an output latch, but it does occur close enough to when the latch is actually triggered to hold.
If all three masking effects fail to occur, the propagated pulse becomes latched and the output of the logic circuit will be an erroneous value. In the context of circuit operation, this erroneous output value may be considered a soft error event. However, from a microarchitectural-level standpoint, the affected result may not change the output of the currently-executing program. For instance, the erroneous data could be overwritten before use, masked in subsequent logic operations, or simply never be used. If erroneous data does not affect the output of a program, it is considered to be an example of microarchitectural masking.
Read more about this topic: Soft Error
Famous quotes containing the words soft, errors and/or logic:
“But Thou that know’st Love above Intrest or lust
Strew the Myrtle and Rose on this once belov’d Dust
And shed one pious tear upon Jinny the Just
Tread soft on her Grave, and do right to her honor
Let neither rude hand no ill Tongue light upon her
Do all the smal Favors that now can be done her”
—Matthew Prior (1664–1721)
“The weak have one weapon: the errors of those who think they are strong.”
—Georges Bidault (1899–1983)
“...some sort of false logic has crept into our schools, for the people whom I have seen doing housework or cooking know nothing of botany or chemistry, and the people who know botany and chemistry do not cook or sweep. The conclusion seems to be, if one knows chemistry she must not cook or do housework.”
—Ellen Henrietta Swallow Richards (1842–1911)