A method and system for accurately imaging scenes having large brightness variations. An index is used to unlock scoreboard entries when a terminating event associated with that entry’s instruction has occurred. The intake manifold receives a substantially inert gas stream and the output manifold receives a stream of pressurized gas from the compressor. On an upper surface of an n+-type semiconductor region for source in the memory cell there is formed a silicide layer whose end portion on the memory gate electrode MG side is defined by the second side wall. Here, a bolt supports the driving roller so that it is centered, and end sections of the bolt projecting from the driving roller are supported in bolt eyes of the tappet housing. The wheel axles include, in various embodiments, simple manually manipulable methods to latch each wheel in the operative or stowed flat positions, which effectively allows the device to fold to a flat profile without any wheel being detached.