It looks like the maximum amount a track can hold is 79 7-bit words [1], which comes out to 553 bits. Theoretically, a parallel reader would need 553 sensors, w

It looks like the maximum amount a track can hold is 79 7-bit words [1], which comes out to 553 bits. Theoretically, a parallel reader would need 553 sensors, which seems fairly easy given today's manufacturing standards. [1] http://money.howstuffworks.com/personal-finance/debt-management/credit-card2.htm http://money.howstuffworks.com/personal-finance/debt-managem...