公开(公告)号：CA2046720A1

公开(公告)日：1992-03-01

申请号：CA2046720

申请日：1991-07-10

Applicant: IBM

Inventor： BEARDSLEY BRENT C ,  BELLO KEITH A ,  BENHASE MICHAEL T ,  CLARK FLORENCE J ,  HUNTER PAUL W ,  NORDAHL DONALD M

IPC: G06F13/12 ,  G06F3/06

Abstract: A control unit (12) for DASD operation to transfer data between the device (13) and a buffer (16) and between a channel (11) and a buffer (16). In that manner the channel and device are enabled to transfer data independently of each other. Mechanisms are provided for communication between the channel interface process in the control unit and the device interface process in the control unit. Some of these mechanisms are stored with the record in the buffer and others are stored in control storage. Principle communicating mechanisms include a device record pointer, a channel record pointer, a next operation field, a device state indicator, record control flags, and two buffer pointers.

公开(公告)号：CA1119311A

公开(公告)日：1982-03-02

申请号：CA337645

申请日：1979-10-15

Applicant: IBM

Inventor： HUNTER PAUL W ,  MALACCORTO ALEXANDER E

IPC: G06F13/10 ,  G06F3/06 ,  G06F13/12 ,  G06F13/00

Abstract: IMPROVED DAS DEVICE COMMAND EXECUTION SEQUENCE A method and means are provided to increase the effective data transfer rate between a direct access storage device (DASD) and a central processing unit (CPU) communicating with the DAS device through a channel and a DASD control device. A command issued to the DAS subsystem which requires mechanical motion in the DAS device is stored in the subsystem and the subsystem provides a response to the channel indicating that the command has been carried out, without actually carrying out the command. The channel responds by issuing one or more additional commands in the chain to the subsystem which may be carried out without mechanical motion. When a command is issued to the subsystem which again requires mechanical motion of the device, the control device causes the stored command to be executed essentially simultaneously with the newly received command. This execution of the stored command out of its normal sequence and in parallel with another command involving mechanical motion of the DAS device decreases the time required to perform operations with the DASD subsystem. SA9-78-061