초록 ▼

A microcomputerized postage meter that provides high degrees of security and fault tolerance. The meter maintains data security under low power conditions by the use of functionally nonvolatile memory units. Register and other data which must survive normal and abnormal losses of power to the meter

A microcomputerized postage meter that provides high degrees of security and fault tolerance. The meter maintains data security under low power conditions by the use of functionally nonvolatile memory units. Register and other data which must survive normal and abnormal losses of power to the meter electronics are stored in dual redundant battery augmented memories (hereinafter designated BAMs). Upon detecting an error condition, the microcomputer writes an appropriate fault code to the BAMs. A mechanism for disabling the meter includes dual redundant flip-flops which are set to a “faulted”state upon detection by the microcomputer of a failure condition. These flip-flops are powered by the BAM batteries. They cannot be reset except by physical access to the meter interior, which access is only available to authorized personnel at the factory. The fault flip-flops are also set when the microcomputer fails to properly execute its own operating program. Once the meter has been set to a “faulted”state, the fault flip-flops hold two signals, MPCLR ans SYSCLR, true. The BAM contents may still be read out independently of the microcomputer which is prevented from accessing the BAMs. This is accomplished by allowing power necessary to read the BAMs to be supplied to the BAMs without supplying power to the microcomputer. Moreover, even if the microcomputer is powered, MPCLR prevents it from executing instructions and SYSCLR isolates it.

대표청구항 ▼

In a microcomputerized postage meter having a microcomputer programmed for supervising the printing operation and for generating, maintaining, and verifying accounting information, a postage printing mechanism coupled to the microcomputer for printing postage in response to instructions from the mic

In a microcomputerized postage meter having a microcomputer programmed for supervising the printing operation and for generating, maintaining, and verifying accounting information, a postage printing mechanism coupled to the microcomputer for printing postage in response to instructions from the microcomputer, and input means coupled to the microcomputer for communicating data to the microcomputer, the microcomputer and printing mechanism being located within a secure housing, the improvement comprising: first and second independent non-volatile memory means coupled to the microcomputer and located within the secure housing; the programmed microcomputer including means for storing a particular item of accounting information in each of corresponding locations of the first and second non-volatile memory means, means for retrieving the contents of the corresponding locations, and means for comparing the contents of the corresponding locations; and non-user-resettable means coupled to the microcomputer for deactivating the meter in response to a disagreement between the contents of the corresponding locations, the non-user-resettable means for deactivating the meter being located within the secure housing, and, once set, being beyond control of the microcomputer; the non-user-resettable means for deactivating the meter having associated means coupled to the first and second non-volatile memory means for preventing the microcomputer from writing data into either of the first and second non-volatile memory means and associated means coupled to the postage printing mechanism for preventing activation of the postage printing mechanism.