| 摘要 |
PURPOSE:To reduce hardware by providing a means for storing a correct operation value of data which has been determined in advance, comparing a derived arithmetic value and the correct arithmetic value, and executing a check of stored data. CONSTITUTION:Each ROM data outputted from a mask ROM10 to be tested by an address generated from an address counter 11 is supplied to an adding circuit 12, and its check sum is taken. For instance, the ROM data of an odd address is supplied to high-order data input of the adding circuit 12, the ROM data of an even address is supplied to a low-order data input of the adding circuit 12, and when all data of the mask ROM have been supplied to the adding circuit 12, a check sum is outputted from the adding circuit 12. This check sum is supplied to a comparing circuit 14 and compared with a correct check sum of a register 13. If both the check sums coincide with each other, it is decided that the mask ROM10 to be tested can output normal ROM data, and if they do not coincide, it is decided that there is an abnormal state in the ROM data, namely, the mask 10.
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