| 摘要 |
1,083,375. Record retrieval. INTERNATIONAL BUSINESS MACHINES CORPORATION. May 5, 1966 [May 27, 1965], No. 19904/66. Headings G4A and G4C. In a record retrieval system, indicia for records retrieved are stored and retrieval of a record already retrieved is prevented. When any one of a plurality of processors attempts to access a record in a bulk storage unit (disc or strip), the record address is compared in turn with the addresses of records already accessed but not yet replaced. These addresses are stored in respective rows of an auxiliary store, the rows being scanned by a binary counter until equality is obtained in the comparison or the maximum count is reached. If equality is obtained, the requesting processor is signalled that it must wait. If the maximum count is reached, however, accessing of the bulk storage proceeds and the address is stored in the first free row of the auxiliary store, located by scanning. When the processor returns the record, its address is located in the auxiliary store by the successive comparison process, and deleted. Each row of the auxiliary store stores its own (row) address in one of two sections thereof to indicate whether or not the row is free (used for addressing the auxiliary store). The section used when the row is free may store the invalid (row) address 15 (equal to the said maximum count) when the row is not free, this being used to cause continuation of said search for a free row. One of said two sections may be dispensed with. Accessing may be associative in which case the auxiliary store may hold the keys rather than addresses of accessed records, or the address may form part of the record, be accessed first and used as above.
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