| 摘要 |
PURPOSE:To effectively prevent illegal copying by making it impossible to achieve the same function of the original PLD even if a program data is combined with the other PLD of the same type in such a PLD that a function may be programmed by inputting program data from an external circuit after the power switch is turned on. CONSTITUTION:An address generated by a control circuit 26 is supplied to RAM 22 since scramble is effectuated based on the key data by an address scramble circuit 30. An inverse scramble program data inversely scrambled previously is read from E(E)PROM 24 based on the key data and is then written to RAM 22 in accordance with the scrambled address. Therefore, anyone who does not know the key data cannot copy this PLD. |
