Your query No 1 cannot be answered. Insufficient data.

Your query No 2: For stroing and retrieving data in the EEPROM on the chip ( no external ) proceed as below:

Create two tables : One to store the password + the corresponding pointer to the relevant data.

The second table has the relevant data corresponding to the pointer. The number of Bytes between the address-off two pointers will depend on the data you would like to store.

User enters password.

You check if there is a match in the First table. If YES jump to the relevant point in Second Table. If NO inform so and wait.

ACtually the NO condition can branch further : You can ask user if he wants to create a password or simply say that it is wrong. If you choose the latter option then you have to have a separate routine for creating new passwords.

Have fun. And if you cant let me know...

Raghu