| 摘要 |
<p>PURPOSE:To improve the secret-protection properties in collation of the stored information for a program memory kept in a reading inhibition state by performing the comparison and decision of address information supplied from the outside. CONSTITUTION:When the reading of a program memory 120 is inhibited, an input/output control part 110 is controlled by an inhibiting circuit 100. Then, the output of the data coincidence/discordance signals 161 and 162 are controlled by a data deciding circuit 160 and an address deciding circuit 170. A binary counter 150 increases its value synchronously with a clock signal 186. At the same time, the address information and the program data information are supplied from the outside. The circuit 170 compares and decides the output of the counter 150 with the external address information and outputs an address deciding signal 171. If the address information is discordant, the signal 171 is equal to '0'. Then, the output of both signals 161 and 162 of the circuit 160 is inhibited to the outside of a chip.</p> |
