Browse Prior Art Database

Personal Computer System Adapter Post Error Reporting by Inaccessible Rom

IP.com Disclosure Number: IPCOM000121513D
Original Publication Date: 1991-Sep-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 3 page(s) / 105K

Publishing Venue

IBM

Related People

Anantharam, CV: AUTHOR [+5]

Abstract

This article describes a concept wherein shared memory and mail box are applied to communicate errors from an adapter to a personal computer (PC) system power-on self-test (POST).

This text was extracted from an ASCII text file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 52% of the total text.

Personal Computer System Adapter Post Error Reporting by Inaccessible
Rom

      This article describes a concept wherein shared memory
and mail box are applied to communicate errors from an adapter to a
personal computer (PC) system power-on self-test (POST).

      Some PC system's intelligent adapters restrict the system from
accessing adapter ROM which prevents the system POST from scanning
the adapter

ROM.

  PC system POST scans the ROM on adapters to
determine if they have finished their POST and reported their errors.
The address of the scan is established at installation time.
Intelligent adapters must store their errors on the adapter card
until they can be interrogated.  Operational code is used as the
mechanism for reporting the errors detected by the adapter POST.
That means the user must wait until the operating system (OS) is
loaded, and the adapter card operational code is loaded before it is
known if the card is operational.

      A diagram of the adapter card bus arrangement is shown in Fig.
1.  It can be seen that the PC system code cannot communicate with
the adapter

ROM.

      A work area is established in the adapter RAM.  The address of
the work area is defined at installation time using the options
diskette.  The work area will be used to communicate to the PC system
POST since the system POST cannot communicate directly with the
adapter ROM.  It is not necessary to test the work area before using
it because the results will be the same.  If the work area is not
functional, the adapter will communicate the error to the PC OS
rather than the PC system POST.  There are some precautions that must
be taken:
1.   The adapter RAM must never be degated from the MICRO CHANNEL*
bus throughout the execution of the adapter POST.
2.   The contents of the adapter CPU PAGE register are never altered
throughout the execution of the adapter POST.

      The adapter POST is run to completion.  All errors are reported
to the work area.  The work area is degated when the adapter POST is
complete.  Refer to the flow chart of Fig. 2.

      In the following description, the ROM scan code executed by the
system POST is denoted by RSC and the adapter POST is denoted by APC.

      The adapter RAM work area...