Browse Prior Art Database

Workstation Disconnect Verification Circuit

IP.com Disclosure Number: IPCOM000041724D
Original Publication Date: 1984-Mar-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Johnson, H: AUTHOR

Abstract

In a data processing system, it is important that each in workstation in the system be disconnected from the system prior to its diagnostic testing of its transmitting/receiving circuits in order to prevent interference with other workstations and the workstation controller. The circuit described herein and illustrated in the drawing listens for activity at the communications interface between the workstation under test and the communications line of the data processing system. Referring to the drawing, the driver and receiver of the workstation are tested with a diagnostic wrap test in which data from the workstation microprocessor (not shown) presented at line A is transmitted by the driver over the internal cable to the receiver and detected by the activity detector which consists of edge-triggered flip-flops (e.g.

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Workstation Disconnect Verification Circuit

In a data processing system, it is important that each in workstation in the system be disconnected from the system prior to its diagnostic testing of its transmitting/receiving circuits in order to prevent interference with other workstations and the workstation controller. The circuit described herein and illustrated in the drawing listens for activity at the communications interface between the workstation under test and the communications line of the data processing system. Referring to the drawing, the driver and receiver of the workstation are tested with a diagnostic wrap test in which data from the workstation microprocessor (not shown) presented at line A is transmitted by the driver over the internal cable to the receiver and detected by the activity detector which consists of edge-triggered flip-flops (e.g., 74LS74) 1 and 2, one of which receives inverted input. To prevent interference with other devices in the data processing system, the Activity detector is also used before the diagnostic wrap test is initiated to verify that the workstation has first been disconnected from the rest of the data processing system Verification of disconnect is achieved in the following manner: 1. Flip-flops 1 and 2 are reset to the off state by a microprocesso signal over the Reset line. 2. The microprocessor allows the Activity Detector to listen at the communication interface (connector) for a reasonable length of time (up...