Personal Computer System Adapter Post Error Reporting by Inaccessible Rom
Original Publication Date: 1991-Sep-01
Included in the Prior Art Database: 2005-Apr-03
Anantharam, CV: AUTHOR [+4]
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).
Personal Computer System Adapter Post Error Reporting by
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).
system's intelligent adapters restrict the system from
accessing adapter ROM which prevents the system POST from scanning
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
A work area
is established in the adapter RAM. The
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
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.
POST is run to completion. All errors
to the work area. The work area is degated when the adapter POST is
complete. Refer to the flow chart of Fig. 2.
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...