Soft Error - Soft Errors in Combinational Logic

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:

    After that it came to my door. Now it lives here.
    And of course: it is a soft sound, soft as a seal’s ear,
    that was caught between a shape and a shape and then returned to me.
    Anne Sexton (1928–1974)

    Of all the errors which can possibly be committed to the education of youth, that of sending them to Europe is the most fatal. I see [clearly] that no American should come to Europe under 30 years of age.
    Thomas Jefferson (1743–1826)

    What avail all your scholarly accomplishments and learning, compared with wisdom and manhood? To omit his other behavior, see what a work this comparatively unread and unlettered man wrote within six weeks. Where is our professor of belles-lettres, or of logic and rhetoric, who can write so well?
    Henry David Thoreau (1817–1862)