Stan visualized the flow chart of the machine as he approached.
An archaic form of visual control-flow specification employing arrows and "speech balloons" of various shapes.
Hackers never use flow charts, consider them extremely silly, and associate them with COBOL programmers, card wallopers, and other lower forms of life. This attitude follows from the observations that flow charts (at least from a hacker's point of view) are no easier to read than code, are less precise, and tend to fall out of sync with the code (so that they either obfuscate it rather than explaining it, or require extra maintenance effort that doesn't improve the code).
See also Program Design Language.