Systems and methods are disclosed for maintaining an accurate program-visible machine state of a computer. A backup system and method is provided in order to return the visual state of the computer to a previous state if an instruction generates an exception. In an embodiment, a first tag and a second tag are received from a tag queue concurrently. First data, which is associated with the first tag, is received and stored in a first register associated with the first tag. Second data, which is associated with the second tag, is sent from a second register associated with the second tag to a backup queue.