Logic on main storage memory cards for insertion and extraction of tag

Abstract

A data processing network includes multiple processing devices, multiple memory cards of main storage, and a shared interface. Each of the memory cards includes memory arrays, an internal register for temporarily storing a pointer data word read from the arrays, and logic circuitry. When one of the processing devices sends a tag bit extraction or tag bit insertion command to one of the memory cards, the pointer to be modified is retrieved from a selected address in the memory arrays and latched into the internal register. The logic circuitry provides the tag bits to an AND logic gate and provides the AND gate output to the processor in the case of tag bit extraction. For tag bit insertion, the circuitry applies the pointer from the arrays and a tag bit input from the processor, as inputs to a multiplexer and provides the multiplexer output back to the selected address in the arrays.