| 摘要 |
PURPOSE:To eliminate the need to modify a check program even when more ROMs are installed, by advancing a check on the storage contents of a ROM according to the storage contante of another ROM. CONSTITUTION:When three ROMs are used, ADRSs 1-3 of each ROM are set at parts 6-8 of address parts 5 of the ROMs 1, 2 and 3. The checksum of those three ROMs is stored in a ROM dedicated to checksum storage. In this ROM, the starting addresses 9 of the ROMs 1-3, the number of bytes 10 as the numbers of data, and the checksum 11 are stored as blocks of each ROM successively in the form of the ASCII code. A check on the storage contents starts at the starting address of the ROM and ends with an end code 18. Consequently, even when ROMs are installed more, the contents of the ROM for the checksum is only varied slightly. |
