A fatal failure in the execution of a
machine language instruction resulting from the
processor detecting
an anomalous condition on its
bus. Such conditions include
invalid address alignment (accessing a multi-byte number at an
odd address), accessing a
physical address that does not
correspond to any device, or some other device-specific
hardware error. A bus error triggers a processor-level
exception which
Unix translates into a "SIGBUS"
signal
which, if not caught, will terminate the current process.