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Utilization of the BAL Microcode Instruction to Provide Reference Codes for Analyzing Logic Malfunctions

IP.com Disclosure Number: IPCOM000048340D
Original Publication Date: 1982-Jan-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Lowdermilk, DJ: AUTHOR [+2]

Abstract

In prior microcoded devices, "error" codes indicating a particular type of machine problem had to be generated within the microcode routine detecting the problem, and then stored in a predetermined area within the machine. With this method, additional coding was required for each error detected and cross references were necessary to determine where in the microcode routine the error occurred. If the address of the microcode detecting the error was used to indicate where the error was detected, then as the microcode routine was altered, it was possible for the detecting address to change, requiring the reference documentation to be regenerated.

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Utilization of the BAL Microcode Instruction to Provide Reference Codes for Analyzing Logic Malfunctions

In prior microcoded devices, "error" codes indicating a particular type of machine problem had to be generated within the microcode routine detecting the problem, and then stored in a predetermined area within the machine. With this method, additional coding was required for each error detected and cross references were necessary to determine where in the microcode routine the error occurred. If the address of the microcode detecting the error was used to indicate where the error was detected, then as the microcode routine was altered, it was possible for the detecting address to change, requiring the reference documentation to be regenerated.

Within the microcode for a Synchronizing Channel to Channel Adapter (SCCA), a Branch and Link (BAL) logout table is defined at fixed addresses FFFA to FFA0 to handle the numerous error detecting routines within the SCCA microcode. The table begins at the last location in control storage and proceeds towards zero. In this manner, any new error codes required can be added and the previous codes remain the same.

When an error is detected, the microcode is adapted to branch to a predetermined location in the "BAL TABLE" which will Branch and Link (BAL) to the logout routine for the storing of log information and error codes. The error code is the control storage address that was stored by the BAL instruction in the BAL TABLE...