GB1233484A - - Google Patents

Abstract

1,233,484. Associative stores; data processing. INTERNATIONAL BUSINESS MACHINES CORP. 26 July, 1969, No. 37665/69. Headings G4A and G4C. In an electronic digital data storage system in which data is transferred between a data register and any word register of an associative array, the word register being selected by an associative search using orders of the data register specified by a mask register, a mask store is provided having a plurality of mask data registers, the contents of one or more of which are loaded into the mask register. Different masks may be loaded during the first (selection) and second (read/write) phases of a store cycle. A control store provides search arguments for the main associative store (above), an associative function store which controls the latter, and for the mask store which is also associative (but need not be). The main store may perform table-look-up operations. The argument bit positions of the mask store have possible states 0, 1, " don't care". If two or more words are read from the mask store (or other associative store) simultaneously, they are ORed together. The main and mask stores may be duplicated, the main stores receiving the same data and same function control signals, and the mask stores receiving the same search argument. The data may include extra function bits, so by using different masks on them, the main stores may perform different operations from each other. Each main store may perform an operation (e.g. add in real-time process control applications) on a respective character of a multi-character word, by table-look-up. If no mask is selected for a given main store (due to no match in the mask store), this may inhibit the respective main store. Alternatively, data read from one main store may go to the data register of the other, optionally with interchange of selected fields. With this serial arrangement the first main store may generate partial sum and carries, and the second may add carries into the partial sum, thus performing addition by table-look-up. Main stores may have two data registers, and in the serial arrangement this allows the second store not to be used for operations other than addition by using, in these operations, the data register not communicating with the second store, the empty state of the data register of the second store signifying to it no-operation. Each data register may have a respective mask register. The control store may be non-associative and addressed by an instruction counter, or associative and using a " next " operation to get successive instructions. The associative stores may be as in Specification 1,186,703 referred to.