Browse Prior Art Database

Fault Isolation for a Control Unit

IP.com Disclosure Number: IPCOM000090715D
Original Publication Date: 1969-Jun-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Nemazee, P: AUTHOR

Abstract

Detailed fault isolation is obtained in a control unit which utilizes read only storage ROS control without attaching any test devices or stopping the operation of the control unit. This is accomplished by introducing two new channel commands, diagnostic write and diagnostic read. Read-write commands, as they exist, are essentially the same signals but are interpreted by the ROS controlled control unit as diagnostic write and read commands. The only additional equipment necessary for performing the fault isolation is a buffer unit which is large enough to accept a full micro-instruction together with a full control unit log-out.

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Fault Isolation for a Control Unit

Detailed fault isolation is obtained in a control unit which utilizes read only storage ROS control without attaching any test devices or stopping the operation of the control unit. This is accomplished by introducing two new channel commands, diagnostic write and diagnostic read. Read-write commands, as they exist, are essentially the same signals but are interpreted by the ROS controlled control unit as diagnostic write and read commands. The only additional equipment necessary for performing the fault isolation is a buffer unit which is large enough to accept a full micro-instruction together with a full control unit log- out. The actual diagnostic write command which transfers a micro-instruction across the channel to the buffer as well as the diagnostic read command to retrieve the log-outs and to analyze the log-outs to determine the field replaceable units which are in error are issued by a program. The micro- instruction can be put into the read-only storage data register ROSDR and executed in two ways. The read-only storage address register can address the micro-instruction which is read out of storage into the ROSDR or the micro- instruction is directly gated into ROSDR with ROS access to ROSDR blocked until the micro-instruction is executed.

The control unit can be tested and the fault located while the control unit is on-line. The control unit can be used during the execution of the test in those periods when the control unit is not executing the diagnostic commands. No manual intervention is necessary by an operator to perform the test. The test is actually run as a job in the operating system stream with no disturbance in user operation. The speed of the test is governed by the natural channel control unit data transmission rate of the system and not...