| 摘要 |
PURPOSE:To shorten diagnosing time by setting a register and a diagnosis auxiliary control circuit between a data processing circuit and a memory and writing diagnosis data stored in the register in the memory right after the data is read out. CONSTITUTION:A data processing circuit 1 writes successively the diagnosis data in the entire area of a memory 2 via a bus and a register 3. Then the circuit 1 stores once the diagnosis data to be written next in the register 3 and the reads the data out of the entire area of the memory 2. In this case, different diagnosis data held by the register 3 are written in the memory 2 by a diagnosis auxiliary control circuit 4 right after the data is read out of the memory 2. The circuit 1 performs two access actions in a single cycle to read the data out of the memory 2 in a second step where the diagnosis data are read out of the entire area of the memory 2 and immediately writes the diagnosis data. Thus the access frequency of the circuit 1 to the memory 2 is decreased and a memory diagnosis test is carried out in a short time.
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