发明名称 |
Method and apparatus for controlling reselection of a bus by overriding a prioritization protocol |
摘要 |
The present invention provides a method and apparatus for dynamically modifying the priority of access to a bus, where the bus has control and arbitration functions distributed among the devices coupled to the bus, with each device having a fixed priority level. Access to the bus by particular devices is selectively inhibited, preventing them from asserting their fixed priority level. In a preferred embodiment, the present invention provides control over the reselection of a SCSI bus by a plurality of SCSI devices coupled to the bus by providing a pseudo busy signal to SCSI devices from which reselection is not desired. In this fashion, an initiator may issue a plurality of commands to the SCSI devices and control the order in which the devices will be serviced when ready. A plurality of pseudo busy circuits are provided, with one coupled to each device on the bus. Each pseudo busy circuit is controlled by a control signal from the initiator. The pseudo busy circuit intercepts the busy line of the SCSI bus and provides a pseudo busy signal to the busy line input of the device when instructed by the initiator; although this requires additional control lines in conjunction with the SCSI bus, it allows the use of standard peripherals connectors and controllers designed for the SCSI bus.
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申请公布号 |
US5414818(A) |
申请公布日期 |
1995.05.09 |
申请号 |
US19900505746 |
申请日期 |
1990.04.06 |
申请人 |
MTI TECHNOLOGY CORPORATION |
发明人 |
HENSON, LARRY P.;GAJJAR, KUMAR;IDLEMAN, THOMAS E. |
分类号 |
G06F13/36;G06F13/374;(IPC1-7):G06F13/42 |
主分类号 |
G06F13/36 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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