Hi Vu,

The lookup table needs only occupy 50 bytes - out of 4096 No problem there. What you want to do is pretty simple to do. Unfortunately I am out of the UK on business for a week, so I haven't time to help now, but the various bits and pieces you need will be in the forum somewhere.

Start by getting a feel for handling serial communication first, the translation to EIA will be easy.

How are you going to do the coupling ? Switch on and off LED's across the reader holes ?

Steve
Steve