专利名称：Data processing systems and methods of
operating such systems to transfer databetween the main store and a secondarystore
发明人：Meltzer, David申请号：EP81101358.0申请日：19810225公开号：EP0037459B1公开日：19860514
摘要：A data processing system and a method of operating the system to transferdata between the main store and a secondary paging store are described. The operationsto prepare the secondary paging store for the data transfer relative to the main storeare overlapped in time with chaining operations of an input-output channel inter-connecting the stores for preparing a command defining the transfer operation. Thepaging store is organized for sequential access to page records and the operations toprepare the paging store include a calculation of a \"roll mode\" displacement factor whichdefines a randomly chosen displacement position in a designated page area for beginningthe transfer with minimized latency. This displacement factor is calculated as a function ofchannel operational characteristics as well as the bit timing rate of the paging store. Thedisplacement calculation is also adapted for a paging store having different timing ratesfor transferring data and regenerating stored data. The displacement factor is stored in abuffer register and conditionally transferred to the channel when the channel nextselects the paging store in association with the chained command. The transfer of the
displacement factor is conditioned on the timing of the channel selection relative to theaccessibility timing of the displacement position. If the selection is late the response tothe selection is delayed until a new factor is calculated. Such re-calculations will berelatively infrequent in a system which is not overloaded with channel contention activity.
申请人：International Business Machines Corporation
地址：Old Orchard Road Armonk, N.Y. 10504 US
国籍：US
代理机构：Lewis, Alan John
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