| 摘要 |
PURPOSE:To investigate an actual defective density of a memory using an ECC circuit by preventing to pass the reading data of a memory cell through an Error Correcting Code (ECC) by an external signal. CONSTITUTION:When an input goes to be H by an external signal through an input terminal 1 and a protecting circuit 6, an output of an ECC control signal generating circuit 2 is inverted to H, a transistor 8 of a changing-over circuit 4 is on and a transistor 7 is off through an inverter 9. Thus, reading data from a memory cell are serially outputted without passing through an ECC circuit 3. As this result, the actual defective density of the memory using the ECC circuit can be investigated.
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