Bull Hn Information Systems Italia S.p.a.

Honeywell Bull Italia S.p.a.

Claudio Fiacconi

Antonio Franzosi

A cache memory when receiving an operand read request and the operand address from a central processing unit responds with a signal indicative of an operand being available in the cache memory before having checked if such operand is effectively in the cache or if in a previous operand request, the effective operand presence in the cache had occurred or started a memory read operation before having checked if such operand is effectively not present in the cache or if in a previous operand request, the effective absence of the operand from the cache has occurred. The decision among the two alternatives is determined by state logic which stores the previously occurred HIT condition denoting the requested operand presence in the cache or MISS condition denoting the requested operand absence from the cache memory. The states of these conditions are updated during the course of a current read operation if a predicted HIT condition is followed by an effective MISS condition or if a predicted MISS condition is followed by an effective HIT condition.

Hit predictive cache memory

A multiprocessor system architecture in which two processors are each provided with an autonomous bus and the two buses can be selectively connected to each other to form a unique system bus which enables access by all processors to common memory resources connected to one of the autonomous buses. The communication between processors takes place through messages stored into mailboxes located in the common memory. The presence of a message is evidenced by a notify/interrupt signal generated by a logic unit to which each processor has access to modify and verify the logic unit's status, using the processor's autonomous bus, and without interfering with operations using the other autonomous buses of the other processor. Such verification and access does not require access to common memory resources nor polling operations to verify the status of messages stored into 'mailboxes'.

Growing community of inventors

Arcore, Italy

Claudio Fiacconi