Unisys Corporation

Western Digital Technologies, Inc.

Richard Mike Holmes

Leon A Krantz

Mark Jeffrey Tadman

A conflict detection method for a disk drive controller is used to handle a conflict potentially occurring if the execution sequence of queued commands sent from a host to a controller is reordered to optimize disk drive transfers. The conflict detection method determines if there is an address range overlap between two queued commands. If an overlap exists, a conflict flag is set. The controller microprocessor utilizes this flag to restrict command reordering and prevent a conflict from producing erroneous data. Conflict detection and command reordering restriction are facilitated by a queued command RAM and a command FIFO. The queued command RAM stores command parameters indexed by command tag values. These parameters include command direction (read or write), LBA, block count, a valid flag and a conflict flag. The conflict detection method compares the address range of a new command with the address range of valid commands in the command RAM to determine range overlaps. If an overlap exists with a new write command, the conflict flag is set for both the write command and the overlapping commands in the queued command RAM. The microprocessor accesses the queued command RAM to determine which chronologically ordered commands in the FIFO must be executed in sequence.

Conflict detection for queued command handling in disk drive controller

A system whereby a receiving module, in a mixed network of hardware and software-emulated modules, requires an Interrupt before it can use a Get Message OP to access a message from a message queue and which also provides a Fast Empty of messages in a message queue by eliminating the need for an Interrupt before each succeeding message access.

Interrupt handling system for message transfers in network having mixed

A method for message transfers between digital modules in a network where some modules are hardware implemented and some modules are emulated in software. An Auxiliary Message Arbitrator Unit utilizes Main Memory storage for messages destined for receiving modules. Algorithmic sequencing means maintains chronological transfer operations of messages and uses hard and soft Interrupt signal queues to inform respective hard and soft modules of pending messages for them to retrieve.

Control method for message communication in network supporting software

A method and system of message transfers in a multiple sender-multiple receiver network provides a specialized sequence for a Sender to acquire a message slot and place a message in a message queue, and a retrieval sequence for the Receiving module that insures message transmission integrity and proper chronological sequence of message delivery.

Message transfer system and control method for multiple sending and

A hardware message transfer control unit designated as the Auxiliary Message Arbitrator Unit (AMA) manages message transfers and transfer protocols in a network of sending and receiving digital hardware modules. Flexibility of network expansion to include software emulated digital modules to the hardware modules is provided in RAM circuitry at the message transfer control unit.

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Mission Viejo, CA, United States of America

Richard Mike Holmes