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Invoking Error Recovery Procedures

IP.com Disclosure Number: IPCOM000048253D
Original Publication Date: 1982-Jan-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Findley, GI: AUTHOR

Abstract

Rather than have operating systems in host invoke device-dependent error recovery procedures (ERPs) which require modification of the host programming each time a different device is attached to a host, peripheral systems supply sense bytes having so-called ERP action codes. The ERP action code selects a specific ERP to be invoked by the host. Accordingly, the peripheral system selectively denominates which ERP is best for solving its problems and which produces host independencies. In this manner a set of global ERPs for all devices of a given character, such as printers, tape recorders, disk files, communication processors; etc., can be employed. Ideally, the ERP is both device and situation independent. That is, there is a set of global ERPs for all printers, another set of global ERPs for all disk recorders, etc.

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Invoking Error Recovery Procedures

Rather than have operating systems in host invoke device-dependent error recovery procedures (ERPs) which require modification of the host programming each time a different device is attached to a host, peripheral systems supply sense bytes having so-called ERP action codes. The ERP action code selects a specific ERP to be invoked by the host. Accordingly, the peripheral system selectively denominates which ERP is best for solving its problems and which produces host independencies. In this manner a set of global ERPs for all devices of a given character, such as printers, tape recorders, disk files, communication processors; etc., can be employed. Ideally, the ERP is both device and situation independent. That is, there is a set of global ERPs for all printers, another set of global ERPs for all disk recorders, etc.

The figure shows the host having an operating system with the global ERPs. Peripheral system A is a first high performance peripheral system accenting high speed operation with moderate quality. Peripheral system B is a high quality system with lower speed of operation. Either system can report the same error; the resultant error can involve invoking a different ERP, as indicated by the ERP pointers ERPP and ERPP'

Examples of ERP action codes include invoking a global ERP for all command reject, data check and specification check type of errors. ERP can indicate an unrecoverable error for exiting from the ERP. Another ERP pointer can be used for all abnormal operator intervention required outward error recorder record, and exit from the ERP. After the error is corrected by operator intervention, the channel program would restart at the failing channel command word (CCW). Another ERP point...