A cache memory for a data processing system having a tag array in which each tag word represents a predetermined plurality or block group of consecutively addressable data block locations in a data array. The lower order set address bits concurrently access the tag word and its associated group of block locations in the data array while individual blocks within the group are accessed by supplemental block bits. Each tag word read out must compare equal with the high order bits of the address and...

A minicomputer system is disclosed having a megabus with a plurality of processors and/or subprocessors, input/output (I/O) units and including logic for enabling the detection, decoding, storage and dispatching of data and instructions between the megabus and associated processors. The logic detects information addressed to its associated processors and synchronizes the transfers between the independently timed asynchronous processors and the units attached to the megabus.

A pipelined register cache for increasing a computer processor's execution speed by reducing the time required to access register data. A register cache is implemented to keep often-used registers in high-speed storage immediately available to the processor's arithmetic and logic unit (ALU). The register cache is constructed using a number of individual register stages which are connected in series such that the register information contained in each register stage is passed from one register st...

A data processing system including a data cache with the capability to selectively zero the contents of the data cache. The invention includes a multiplexor arranged to provide a parallel data output that is greater than the parallel data input from either a central processing unit or from a memory that are each connected to access the data cache. This multiplexor is selectively controlled to provide a parallel data output of zeroes upon the decoding of a specific zeroing instruction.

Each housekeeping command calls for a corresponding combination of write back and flag reset operations. In laundering, a write back operation is performed for owner entries in a specified address set without invalidating those entries. In flushing, a launder is followed by a flag reset invalidating the entries in the address set. Also, the command indicates which of the valid flags should be reset. In demapping, only the flags making an entry inaccessible to the cache's processor are reset. The...

A portable beach cache having a plurality of fabric panels and rigid support members arranged in a picture frame configuration for sheltering the user from wind and wind-blown debris, such as sand. Fold-out feet provide support in soft sand. A handle is provided to simplify carrying and a hook and loop strap secures the portable beach cache in its stowably disposed position. The portable beach cache is compact when folded and light enough to be easily carried by hand. A second embodiment is disc...

A multiprocessing system includes a cache coherency technique that ensures that every access to a line of data is the most up-to-date copy of that line without storing cache coherency status bits in a global memory and any reference thereto. An operand cache includes a first directory which directly, on a one-to-one basis, maps a range of physical address bits into a first section of the operand cache storage. An associative directory multiply maps physical addresses outside of the range into a ...

In a data processing system, a paged memory management unit (PMMU) translates logical addresses provided by a processor to physical addresses in a memory using translators constructed using translation tables in the memory. The PMMU maintains a set of recently used translators in a translator cache. In response to a particular lock value contained in the translation tables in association with the translation descriptor for a particular page, the PMMU sets a lock indicator in the translator cache...

A cache memory system maintains an ordered linked list of cache items having scores that are positively correlated with frequencies of access and negatively correlated with a size that is determined as a number of bytes of each item plus an overhead associated with the linked list. In addition to data and linking pointers, the list segments each include a hit count and a byte count. In a method for managing cache memory forms the linked list by adding segments for newly requested data and deleti...

A memory system which comprises a mainstore for storing lines of data and a buffer store for storing lines of data that are a subset of the data stored in the main store. The buffer store is comprised of a plurality of associativities. A line of data stored in the buffer having a given address may be stored in any one of the plurality of associativities. A tag store stores a tag for the associativities. A field from a buffer store address is compared with the stored tag in the tag store to produ...