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 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 s...

This invention is directed to a memory system that determines which blocks of a set of associative blocks in cache memory are unavailable for replacement. This is accomplished by operating the memory system to maintain a duplicate set of tags which track block ownership for this cache pursuant to a "snoopy" protocol. In addition, the cache system maintains a bit associated with each memory address to indicate whether any data blocks resident in it have been locked. The interlock status of the da...

The invention comprises a system bus apparatus and method for a multi-arm, multiprocessor computer system having a main memory and localized buffer cache memories at each processor. Each block of data in a cache includes tag bits which identifies the condition of the data block in relation to the corresponding data in main memory and other caches. The system bus (SYSBUS) comprises three subparts; 1) a MESSAGE/DATA bus, 2) a REQUEST/GRANT bus and 3) a BCU bus. The MESSAGE/DATA bus is coupled to e...

A method and apparatus is provided for associating in cache directories the Control Domain Identifications (CDIDs) of software covered by each cache line. Through the use of such provision and/or the addition of Identifications of users actively using lines, cache coherence of certain data is controlled without performing conventional Cross-Interrogates (XIs), if the accesses to such objects are properly synchronized with locking type concurrency controls. Software protocols to caches are provid...

An enhanced processor lock cycle management system for computer systems including a processor 10 and a cache memory controller 12 which accommodates existing methodologies and provides an enhanced mode wherein processor lock cycles are not passed to the controlled 12 but control of the system bus 14 by controller 12 is maintained by inhibiting hold requests to the controller 12 by other system elements.

A multi-processor (MP) system having shared storage is provided with locking of exclusivity status and read only status in multi-processor caches. The multi-processor system includes a plurality of processors, a shared main storage and a storage control element (SCE). The storage control element includes a global access authorization table (GAAT). Locking of exclusivity status in multi-processor caches is accomplished by providing at each processor a local access authorization table (AAT) contai...

In an information processing apparatus composed of two or more processor units each including a cache memory and a processor which accesses stored data via the cache memory, and a main storage, a cache memory control method in which, using information concerning control object data, such as identification of a storage area and whether or not the data are program data, a judgment is made as to whether or not the data has a high possibility of being used by another processor. If the data has a hig...

A multiprocessor computer system which maintains cache coherency includes first and second microprocessors each having an associated cache memory storing lines of data. Each line of data has associated protocol bits that indicate a protocol state consistent with write-through, write-back, or write-once cache coherency policies that are selected via a protocol selection terminal for different system configurations. In one configuration, the output and external address terminals of the first micro...

A processor apparatus for use in a multiprocessor computer system having a main memory storing a plurality of data items and being coupled to a bus operating according of a SNOOPY protocol. The processor apparatus includes a processor, a primary cache, a backup cache and a bus interface. The backup cache memory a first TAG store comprising a plurality of VALID indicators, one VALID indicator for each of the data items currently contained in the backup cache memory. The primary cache memory inclu...