| 摘要 |
PURPOSE:To check the data of a memory with more highly accuracy by having a parity check for each byte and each group respectively with each application of a writing electric power supply to decide the propority of the parity check. CONSTITUTION:When a sales price is written from a keyboard 7 after application of a power supply, a parity check of (0-3)-bit is performed for each row. Then the price is automatically written in a memory area of the 7th bit. When the writing is through with the data up to the 24th row, the parity check is given to the vertical column of a memory map to write the data in a memory area of the 25th row for each of (0-7)-bit. When the power supply is applied again after it is cut off, the 1st memory data is read to decide whether the data of (0-3)-bit is less than 10. If this data is less than 10, the parity check is given to (0-7)-bits. If an even parity is obtained from the parity check, the next data is read. Hereafter the parity check is carried out in the same way. |
