Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Microprocessor Error Logout

IP.com Disclosure Number: IPCOM000084035D
Original Publication Date: 1975-Sep-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 3 page(s) / 48K

Publishing Venue

IBM

Related People

Irwin, JW: AUTHOR

Abstract

A microprocessor in a data transfer unit, such as a control unit for a magnetic tape drive, has primary store P for storing operands associated with execution of microprograms in the microprocessor. The execution of these programs, inter alia, control operation of electronic circuits in a data path for transferring signals between upper level units, such as host CPU's, and lower level units, such as magnetic tape drives.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

Page 1 of 3

Microprocessor Error Logout

A microprocessor in a data transfer unit, such as a control unit for a magnetic tape drive, has primary store P for storing operands associated with execution of microprograms in the microprocessor. The execution of these programs, inter alia, control operation of electronic circuits in a data path for transferring signals between upper level units, such as host CPU's, and lower level units, such as magnetic tape drives.

To ensure a high degree of reliability in a complicated set of microprograms, backup or compare store C is added to the configuration. Access to stores P and C is by special commands over lines A and B. The microprocessor generates store addresses which are supplied to both stores, as well as supplying data thereto in a known manner.

Primary store P supplies its output signals not only to the microprocessor, but also to the data path circuits for controlling them. The compare store C supplies its signals to a set of compare circuits, which compare the signal content thereof with the signal content of primary store P corresponding registers.

In normal operation, the microprocessor supplies a set of signals to primary store P and simultaneously in an independent operation, supplies backup identical signals to compare store C. Upon each access of store P contents, compare circuits supply the result of output comparisons of addressed signals in stores P and C. Results of the compare are supplied over the compare line to the microprocessor for microprogram interpretation. An error signal indicating any discrepancy between the signal contents of the two stores, is supplied over the error line to the microprocessor.

In diagnosing subsystem failures, maintenance personnel can supply a controlling signal to the microprocessor for blocking the write gate to compare store C, and for blocking the error line. In this manner, the signal content of the compare stores C can be logged out by use of the compare circuits, without actually having a signal connection from the compare store output lines to the microprocessor or data path. The log...