| 摘要 |
PURPOSE:To shorten the time required for evacuating and restoring the content of registers, by providing registers composed of tag bits for storing unused conditions and evacuating the content of unused registers only at the time of interruptions, and then, restoring the content when the interruptions are terminated. CONSTITUTION:When an interruption is made from the outside during the operation, evacuation of operation registers RG1-RGn is started after the executing instruction is completed. A control section 1 reads out the content one bit by one bit while shifting a register 2 for reference and, when a tag bit is ''1'', outputs the content of a corresponding operation register to a bus 4 and put the content in the evacuating area of the memory 8. If the tag bit is ''0'', the control section 1 evacuates the content to the memory 8 when the tag bit in the next register is found to be ''1''. Therefore, only the content of operations registers being used is evacuated to the memory 8. When the interruption process terminated, data evacuated to the memory 8 are restored to the original registers by a return interrupt instruction.
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