Self-Initiating Diagnostic Program Loader from Failed Initial Program Load I/O Device
Original Publication Date: 1991-Jun-01
Included in the Prior Art Database: 2005-Apr-02
Crandall, DR: AUTHOR [+1]
This article describes a technique for automatically loading a debug handloop for an initial program load (IPL) device.
Self-Initiating Diagnostic Program Loader from Failed
Load I/O Device
describes a technique for automatically loading a
debug handloop for an initial program load (IPL) device.
service representative (CSR) often requires the use
of special diagnostic routines (sometimes called handloops) to cause
activity on selected I/O components within a failing microcomputer
system. This activity is required to enable the CSR to probe suspect
circuitry for potential faults using an oscilloscope or probe to
measure in-circuit waveforms.
If the IPL
device is the failing device and the diagnostic
programs, map packages, and other debug tools cannot be loaded
because of the IPL failure, then previously the only debug tool was a
hand-entered program to cause the I/O device to be active as
described above. Keying in the program required an optional
programmer's console and took as much as fifteen to twenty minutes to
key in and check. This was wasted time installing a tool before a
useful debug could take place.
technique of this disclosure a system handloop is stored
in the IPL device microprogram as data and when an IPL failure is
detected by that microprogram, it automatically loads that diagnostic
handloop into specific locations in the system main storage where it
is ready for the CSR to start using.