Hayles

"Thus voltages at the machine level function as signifiers for a higher level that interprets them, and these interpretations in turn become signifiers for a still higher level interfacing with them. Hence the different levels of code consist of interlocking chains of signifiers and signifieds, with signifieds on one level becoming signifiers on another. "

-N. Katherine Hayles, My Mother Was A Computer. Chicago: University of Chicago Press, 2005.