| 摘要 |
PURPOSE: To enable precise detection of data memory abnormalities and thereby prevent a damage to a drive unit by providing a data checking means for writing digital data of 0 and 1 into and reading such data from a data memory and checking whether or not individual data are equal by collation. CONSTITUTION: When power is supplied to a printer, a CPU 41 writes in an accumulator A digital values 00 (h) in the hexadecimal numbering system corresponding to all the bits of the storage region assigned to each address in an SRAM 47 to be written into. Then the CPU 41 retrieves 00 (h) to the leading address in the SRAM 47, and checks whether the retrieved data equals data 00 (h) present in the accumulator A. If they are equal, the CPU 41 determines that digital values 1 or 0 have been written into the bits of the leading address as instructed, that is, no abnormality is present in the leading address. After adding 1 to the N value to set the digital value to 1, the CPU 41 repeats the similar operation for the other addresses in order to determine whether or not any abnormality is present. |
