Mit mehreren Benutzern zusammenarbeitende Speichereinrichtung für Datenverarbeitungsanlagen

1,056,951. Electric digital calculators. INTERNATIONAL BUSINESS MACHINES CORPORATION. March 29, 1965 [April 6, 1964], No. 13162/65. Heading G4A. In an electronic data processor, sets of instruction words have respective key words associated with them and blocks of storage locations have respective storage key words associated with them, and modification of operand data retrieved from storage in response to an instruction word is prevented in dependence upon a comparison of the key word associated with the set containing the instruction, with the storage key word associated with the storage block originally containing the operand, and in dependence upon non-recognition of a predetermined configuration of data as comprising the key word or the storage key word. Each stored programme and input/output unit has an associated 4-bit key word which specifies the block of storage which the programme or I/O unit may utilize. If the programme or I/O unit may utilize any block, the key word is OOOO. Each block of storage has an associated 4-bit storage key word which specifies which programme or I/O unit may utilize it. If any programme or I/O unit may utilize the block, its key word is OOOO. When the contents of a storage location are retrieved, the corresponding key word and storage key word are examined. If they are equal or if either is OOOO, the contents of the location may be changed. Otherwise the contents are replaced unchanged. The key words and storage key words may be changed under programme control. The key word and storage key word to be examined are placed in respective halves of a register. In one mode of operation, one of them is placed in its half after passing through the other half and a further register.