| 摘要 |
PURPOSE:To check defective RAMs without damaging the contents of the RAM memories, by performing the comparison of data, which undergoes bit inversion for every byte, and performing the comparison of data, which does not undergo bit inversion. CONSTITUTION:In an electronic computing scale, in which a plurality of RAMs are used as a PLU setting memory, a work memory and the like, a RAM checking means performing the following operations is provided: memory is read at every byte, writing and reading are performed again by said memory after the bit inversion, the bit inversion of the read data in performed, the inverted data is compared with the initial read data, the writing and reading are performed again by the memory with the read data intact, and the result is compared with the initially read data. A display means displays the RAM addresses and the like when the defective RAM is detected by said RAM checking means.
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