| 摘要 |
A system for controlling a buffer memory for storing a copy of a portion of a main memory, includes apparatus for detecting whether the address in question exists in the buffer memory in response to an instruction to carry out reading from and subsequent writing into the same address. In the case where the results of the detection are affirmative, reading of the data from the address in question and the subsequent writing of the result of a calculation into the address in question are carried out. In the case where the results of the detection are negative, an instruction for the main memory to read data in the block which contains the address in question is issued. The read data in the block is transferred from the main memory to the buffer memory, the transferred data is written into the buffer memory with the word of the requested address placed as the beginning word of the data, and the beginning word of the data from the buffer memory is picked-up. The picked-up beginning word is transmitted to a calculation portion, and the results of the calculation are written into the same address of the buffer memory in succession to the writing of the beginning word of the data.
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