An asynchronous processor smart card is now starting to appear on credit
and debit cards around the world, it is the chip that is used for most
satellite decoding systems and the new Smart Card for Windows.
In its simplest form it is a single chip processor with onboard memory,
similar, but less powerful, than the average processor in a home computer.
The simile does not stop there, in the same way a home computer has a
keyboard and monitor for inputting data and retrieving results the smart
card has a single input/output pin which it uses to communicate with the
In the same way the home computer needs electricity, the smart card also
needs electricity to be applied, and a PC can be a 500MHz machine, meaning
it requires a clock, so the smart card also needs a clock.