| 摘要 |
A data transfer or replacement system for shifting blocks of data or pages between a high speed, low capacity, working memory and a low speed, high capacity backup store of a data processing system. Each block in the working memory is associated with an "A" and a "B" single bit register. Usage bits are initially inserted into the "A" registers as information from the block is utilized. After one-half of the "A" registers have been identified by associated usage bits, the "B" single bit registers are cleared, and usage bits are inserted into these "B" registers. When one-half of the "B" usage registers are "marked", the "A" registers are cleared and usage bits are then inserted in these "A" registers. Upon the necessity for introduction of additional data from the backup store into the high speed, low capacity working memory, least recently used blocks are identified as those whose associated "A" and "B" registers have not been marked. The new blocks of information are transferred from the backup store into one of the spaces in the high speed store containing such a block of least recently used data.
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