Device for selective change of ROM-data for test and diagnosis purposes e.g. for telecommunications equipment, has comparator for comparing address data of address buses with address data filed in correction data store

摘要

A device for selective alteration of ROM-data has an address bus for transmission of address data (A), a data processing-data bus, a ROM-data bus for transmission of ROM-data (Drom) of a read-only memory (SP), a correction store (R) for storage of correction data, a comparator (2) for comparing the address data (A) of the address busses with the address data filed in the correction data store (R) and for comparing the ROM-data (Drom) of the ROM-data busses with the data processing data (D mu p) of the data processing data busses. A selection unit (1) selects between the ROM-data of the ROM-data busses and the correction data (Dx) of the correction store (R), and a control unit (5) controls the selection unit (1), the comparator (2) and the correction-store (R) depending on programming /read commands of the data processing unit (DV). Independent claims are included for (1) a method of selective programming of ROM-data and (2) a method for reading selectively changed address data