US 5,845,154 AGranted

System for supplying initiator identification information to SCSI bus in a reselection phase of an initiator before completion of an autotransfer command

AssigneeAdaptec, Inc.

InventorShahe H. Krakirian

Life of this patent

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Abstract

A hard disk controller integrated circuit of a SCSI target device comprises a sequencer which causes a SCSI bus to transition from a command bus phase to a data transfer bus phase during execution of an autoread or an autowrite SCSI command without waiting for a communication from a microprocessor of the SCSI target device. In some embodiments, the command is determined to be either an autotransfer command or a non-autotransfer command. If the command is a non-autotransfer command, then the sequencer does not proceed directly to the data transfer phase but rather requires microprocessor intervention before proceeding to the data transfer phase. In some embodiments, an autotransfer command (such as an autoread or an autowrite command) is carried out by the disk drive controller integrated circuit with only two interrupts being generated to the microprocessor: one after receiving the autotransfer command from the initiator; and one after data transfer of the autotransfer command is complete. The hard disk controller integrated circuit automatically sends the status byte and command complete message if there is no queue tag collision as indicated by a cleared tag not okay flag.

Claims3

Dependent claims

A method of transferring data to a SCSI target device comprising:

(a) receiving in the SCSI target device a SCSI data transfer command from a SCSI bus;
(b) determining in a disk controller integrated circuit of the SCSI target device whether the SCSI data transfer command is an autotransfer command;
(c) performing a data transfer for the SCSI data transfer command in the disk controller integrated circuit without waiting for a communication from a processor in the SCSI target device if said SCSI data transfer command is an autotransfer command;
and
(d) disconnecting the SCSI target device from the SCSI bus before a data transfer for the SCSI data transfer command has started, without waiting for a communication from a processor in said SCSI target device, if the SCSI data transfer command is not an autotransfer command, and later reconnecting the SCSI target device to the SCSI bus and performing the data transfer, wherein said SCSI data transfer command comprises initiator identification information, said method further comprising:
before said (c) performing a data transfer, loading a register of said disk controller integrated circuit with said initiator identification information;
before said transferring of (c) performing a data transfer is completed, said disk controller integrated circuit supplying a disconnect message to said SCSI bus;
and
after said disconnect message is supplied to said SCSI bus but before said data transfer in said (c) is completed, said disk controller integrated circuit supplying said initiator identification information from said register to said SCSI bus in a reselection phase of a reconnection to said initiator.

6 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/463,333Filed 5 Jun 1995 · division
Priority: 1 Mar 1994
Granted: 1 Dec 1998
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

G06F 3/061
Specifically adapted to achieve a particular effect: improving I/O performance
G06F 3/0659
Vertical data movement, i.e. input-output transfer; data movement between one or more hosts and one or more storage devices: command handling…
G06F 3/0676
Disk device: magnetic disk device
G06F 13/126
Where hardware is a sequential transfer control unit, e.g. microprocessor, peripheral processor or state-machine: and has means for transferring…