| 摘要 |
PURPOSE:To prevent a third party from reproducing electronic equipment by duplicating the program data of the programmable logic device(PLD), whose functions are programmed by writing the program data from outside, and then applying the data to another PLD of the same kind. CONSTITUTION:An address generated by a control circuit 26 is scrambled by an address scrambling circuit 30 based on the 1st and 2nd key data and supplied to a RAM 22. The program data which are reversely scrambled in advance based on the 1st and 2nd key data are read out of an E(E) PROM 24 and written in the RAM 22 according to the scrambled address. The 1st key data are written in a PLD 20 previously and a user can read the data out, but can not rewrite the data. The 2nd key data can be written by the user, but can not be read out. Consequently, a person who does not know the 2nd key data can not reproduce this PLD. |
