Browse Prior Art Database

Detection of A Working Master Controller by A Slave Card

IP.com Disclosure Number: IPCOM000099594D
Original Publication Date: 1990-Feb-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 2 page(s) / 57K

Publishing Venue

IBM

Related People

Johnson, RD: AUTHOR [+5]

Abstract

This article describes a method and hardware implemen- tation for use in a computer system which enables a slave card to take independent action in case of failure of the master controller.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 70% of the total text.

Detection of A Working Master Controller by A Slave Card

       This article describes a method and hardware implemen-
tation for use in a computer system which enables a slave card to
take independent action in case of failure of the master controller.

      In a distributed I/O adapter environment a master controller
exchanges data and commands with slave cards.  In this environment
the master controller can fail in such a way that it lacks the
ability to tell the slave cards of any problems.  When this happens
the master controller has lost all controls and a way must be found
to inform each of the I/O adapters that the system is no longer
operational.  A software and hardware scheme is disclosed herein to
identify when the master controller is broken and has failed to
communicate with a slave card.

      The master controller accesses a special memory location in the
slave card to determine if any message is pending from the slave card
(a normal polling scheme of transferring messages).  The slave card
maintains a special memory location for status of the card and to
iden tify when messages are waiting for the master.  In the scheme of
this disclosure logic residing on the slave card identifies when the
master has accessed the special memory location in the slave card as
shown in the drawing.

      The logic has the following key functions:
      1.   A monitor register accessible by the slave card firmware
that identifies the memory loca...