| 摘要 |
PURPOSE:To check a syndrome output by extracting the syndrome directly from an output terminal. CONSTITUTION:In accordance with a switching signal obtained from a mode switching terminal 9, a mode switching circuit 8 switches a normal mode for selecting data read out from a data ROM 3' through an error correcting circuit 6' and corrected at its error through a testing ROM 4', a syndrome forming circuit 5', etc., to a mode for selecting a syndrome output from the circuit 5'. In the mode, the syndrome output can be directly extracted from the output terminal 7' to check the syndrome output and whether error correction is executed or not and the error data in the ROMs 3', 4' at the execution of the error correction can be detected, so that search of the cause of a defect or a counterplan for the defect can be properly executed.
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