After registration of a subprogram is completed, a flag indicating that the subprogram has been registered is set. The flag is referred to in response to a subprogram registration request from an IC card reader/writer. Registration of the subprogram is performed only when the flag is not set. A BCC of the subprogram is calculated and stored in a memory upon subprogram registration. When the registered subprogram is to be executed, a BCC of the subprogram read out from the memory is calculated and compared with the BCC stored in the memory. The subprogram is executed only when the two BCCs coincide with each other. If the subprogram has been registered, a BCC check is performed for the registered subprogram. If the BCC check indicates an error, registration of the subprogram is enabled.

Differences between both the code and documentation of a revised generation of software and a previous generation are compared by a digital computer with the intended revisions stored in a release file. When all discrepancies have been eliminated, and for the original generation of the software, actual impacts in the form of the locations in the program where one routine is called by another and where common statements and public variables are used, are compared with expected impacts stored in the release file. When all actual impacts have been identified, the revised software, or the original version in the case of newly created software, is stored in a library with the code and documentation paired, and with each revision of each unit identified for later retrieval and reconstruction of any software generation. The latest generation of the software is then simultaneously verified, preferably by an automated process in a programmed computer, and validated through testing of the auto-linked program in PROMs inserted in the actual hardware.

An electronic computer is disclosed which includes microprogram memory in which a microinstruction is stored, a microaddress control unit for supplying an address to said memory and a register for holding a microinstruction read out of said microprogram memory, the contents of the microprogram memory are stored in the first section of the memory of the microprogram-testing apparatus. The second section of said memory is supplied with data for testing the microinstruction. While the microinstruction is executed, the microinstruction and test data are read out of said memory at the same time, and supplied to the error detector and trace control circuit. The microprogram-testing apparatus further comprises a function switching control circuit, which decides whether the error detector or trace control circuit should be enabled. Where the error detector is selected, then an error in the microprogram is detected. Where the trace control circuit is selected, then the execution of the microinstruction or the halt of said execution is controlled.

In numerical controls of machine tools, the downwards (lengthwise) sum of the programmed information of each system program memory (SP1) is stored in an additional memory. For later checking of the memory contents, the downwards sums of the respective memories on the control side are formed and are compared with the stored information. If a sum deviates, a trouble signal is given out as an indication of the defective memory.

An apparatus and method for detecting and preventing the unauthorized use of computer programs. The program to be protected is arranged to store first key information and a key means which is physically separate from the program is provided to the customer with each program which is sold. The key means stores second key information, and is adapted for association with a computer in which the program is to be processed. Either the first program routine, or one which is performed before a significant part of the program, is arranged to access the first and second key information and to perform a comparison operation. If the first and second information bear a predetermined relationship to each other, then it is known that the appropriate key means has been deployed by the customer on the computer, and that the use of the program is authorized. However, if the first and second key information do not bear said predetermined relationship, it is concluded that use of the program is not authorized, and processing of the program may be terminated.