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:
“Help me to seek, for I lost it there
And if that ye have found it, ye that be here,
And seek to convey it secretly,
Handle it soft and treat it tenderly,
Or else it will plain and then appear:”
—Sir Thomas Wyatt (1503?–1542)
“When people put their ballots in the boxes, they are, by that act, inoculated against the feeling that the government is not theirs. They then accept, in some measure, that its errors are their errors, its aberrations their aberrations, that any revolt will be against them. It’s a remarkably shrewed and rather conservative arrangement when one thinks of it.”
—John Kenneth Galbraith (b. 1908)
“Neither Aristotelian nor Russellian rules give the exact logic of any expression of ordinary language; for ordinary language has no exact logic.”
—Sir Peter Frederick Strawson (b. 1919)