I have recently found in my local electronics shop a very
good example of practical pic'n
They now stock programable rf remote control transmiters
(the type used for car locking/ alarm setting/ garage door openers)
They use a 16c54 and an seeprom to store the codes.
At the shop they have a programing box that you place the remote to
be copied on to then you press the button(s) and it displays
the rf frequencyand memorises the code(s).
Then the code(s up to four) is downloaded into the programmable remote
via a six pin plug (rb4/7,gnd,seeprom)and then the frequency is
adjusted manualy via a trimmer

The code protection system is also very effective if not old
fashioned
It based on selling the product at a reasonable price($14 retail)
thereby cutting the vast profits that can be made on
copying some products

Peter Cousens
email: peter@cousens.her.forthnet.gr  phone: + 3081 324450, 380534
snailmail:  Folia, Agia Fotini, Karteros, Heraklion  Crete, Greece.