| 摘要 |
PURPOSE:To prevent a program malfunction with a parity check related circuit only by changing the parity modes set when the writing and reading operations are carried out with a memory by means of the codes and data. CONSTITUTION:A parity generating part 3 produces an even parity and an odd parity when the codes and data are written to a main memory device 2 respectively. While a parity check par 4 checks an even parity and an odd parity when the codes and data are read out of the device 2 respectively. Therefore the odd parity check is carried out when it is intended to refer to the code part added with an even parity out of the device 2 as a data area owing to the malfunction of a program. Thus a parity error occurs and the program runaway can be prevented.
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