| 摘要 |
PURPOSE:To reduce the software load by providing an instruction for protection of data and using a register for this instruction. CONSTITUTION:A CPU 201 sets a data protecting area on a memory 202 with execution of a data protection setting instruction. Then the CPU 201 executes the data replacement instruction containing the register numbers as operands for registers 207, 208 and 209 including three data describers which indicate the replacement source data 203, the replacement subject data 204 and the preserving destination data 205 respectively. Thus the CPU 201 performs the data replacement processing including preservation for data protection. Furthermore the CPU 201 executes the data protection release instruction containing the number of a data protecting register 210 as an operand at a time point when the no protection is required for data in order to release the data protection memory space set previously to the register 210. Thus the data protection memory space is released. |
