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Using ROS/EEROS As a Pseudo-Service Processor to Verify Field Replaceable Units and for Retry

IP.com Disclosure Number: IPCOM000034437D
Original Publication Date: 1989-Feb-01
Included in the Prior Art Database: 2005-Jan-27
Document File: 3 page(s) / 50K

Publishing Venue

IBM

Related People

Christiansen, RA: AUTHOR [+2]

Abstract

This article describes techniques for using read-only storage/ writable-electronically erasable read-only storage (ROS/EEROS) as a pseudo-service processor to verify field replaceable units (FRUs) and for retry. Conventionally, a ROS/EEROS module was used for initial microcode load (IML) power on tests and had little functional capability during operational mode. The ROS/EEROS module, since it is not required for normal operation during operational mode, can be used to support RAM- loaded code as a back-up if operational code loses control. This gives ROS/EEROS many reliability, availability and serviceability (RAS) capabilities to aid in isolation and recovery, and can reconfigure input output adapter (IOA) resources and report to the system the available configuration.

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Using ROS/EEROS As a Pseudo-Service Processor to Verify Field Replaceable Units and for Retry

This article describes techniques for using read-only storage/ writable-electronically erasable read-only storage (ROS/EEROS) as a pseudo-service processor to verify field replaceable units (FRUs) and for retry. Conventionally, a ROS/EEROS module was used for initial microcode load (IML) power on tests and had little functional capability during operational mode. The ROS/EEROS module, since it is not required for normal operation during operational mode, can be used to support RAM- loaded code as a back-up if operational code loses control. This gives ROS/EEROS many reliability, availability and serviceability (RAS) capabilities to aid in isolation and recovery, and can reconfigure input output adapter (IOA) resources and report to the system the available configuration. The ROS/EEROS can be used in operational modes as follows: Bring-up testing.

On-line testing of FRU bus units.

Some recovery functions.

(Image Omitted)

Mach check vector functions. All vector functions (low core area) as back-up for operational

code. Critical window detection for operational code.

(Any exposure branch point will point to ROS/EEROS

if the random-access memory (RAM) code goes into a loop.) Retry algorithm for high availability. Pseudo-service processor. The pseudo-service processor disclosed herein is shown in the block diagram in Fig. 1. Pseudo in this sense means to eliminate what the service processor used to do for failure scanning and possible recovery. The pseudo-service processor algorithm provides for the following: Controlled sequence to get scan ring data to generate a

reference code. Scan ring reset function for restart. Failure algorithms in ROS/EEROS. Reference Code (RC) for critical failures generates asynchronous error report (AER). For implementation a scan sequencer and registers have to be added as well as a scan clock and a maintenance clock so ROS/EEROS can do functions as a service processor. ROS/EEROS takes over at error time, scanning the logic out via level-sensitive scan design (LSSD) scan clocks and storing results in a buffer or RAM storage. With the controls in this error logic, a comparison is made and a reference code generated. If the error scan code is small, a direct decode to reference code is possible. Also, if the logic has a critical failure, a code is sent to the operational panel (OP) PANEL for display. The other option is that the scan code loaded into RAM can now be analyzed as the scan logic resets the processor unit (PU) and ROS/EEROS algorithms are used to generate a reference code from that scan data. Since most errors are intermittent, the PU is...