title: What sort of data do credit card readers output?
body: <p>What sort of data do credit card readers output? I know that many have drivers that automatically translate data into something useful, but what sort of raw data is there? I'm referring to card readers like the free ones given out by <a href="http://squareup.com" rel="nofollow" title="Square">Square</a> that input data via the microphone port of a device. Do those sort of readers just pull raw data straight from a card to be interpreted by the software, or do the card readers themselves do any sort of data formatting.</p>