| 摘要 |
PURPOSE:To prevent the value of a register from being undesirably changed due to the result of internal operation processing by providing a data processor with a means for inhibiting data transfer from an internal transfer bus to a prescribed register in accordance with the rewritten state of the register before transferring a required internal operation processing result to the register. CONSTITUTION:The data processor is provided with the write inhibition control means 36 for controlling the inhibition of data transfer from the internal transfer bus to prescribed registers REG1 to REGn in accordance with the written state of the registers REG1 to REGn through an interface bus IB before transferring a required internal operation processing result to the registers REG1 to REGn through an internal transfer bus. Namely the means 36 is driven so as to prevent the values of the registers REG1 to REGn rewritten on the basis of an external instruction from being undesirably changed due to the immediately preceding internal operation processing result. |
