bus error

In computing, a bus error is generally an attempt to access memory that the CPU cannot physically address. Bus errors can also be caused by any general device fault that the computer detects. A bus error rarely means that computer hardware is physically broken - it is normally caused by a bug in a program's source code.
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<processor> 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.
(2000-04-04)