1.2.3 IML, POST, and BIOS
The Model 90 uses Initial Machine Load (IML) to store the power-on
self-test (POST) and Basic Input/Output System (BIOS) code. With IML,
some of the code is stored in ROM and is used for preliminary testing
during power-on; but the balance of the POST and BIOS code, called the IML
image, is stored in a protected partition on the default hard disk drive.
This IML image is loaded onto the default hard disk drive at the time the
system is manufactured.
At power-on, the first stage of POST is started from ROM. During this
first stage, POST performs the following functions:
Checks some basic system-board and processor-board functions
Initializes the video function
Checks the memory subsystem
Verifies that the default hard disk drive is functioning
Verifies that the IML image is copied in the protected partition of
the default hard disk drive.
When the first stage of POST is complete, the IML image is loaded into RAM
from the protected partition on the default drive. The second stage of
POST is started from RAM. It performs additional tests of the hardware
and initializes the system. When the second stage of POST is complete,
system control is given to the operating system.
The partition also includes the system programs and the customer and
advanced diagnostic programs. The partition is not affected when the
drive is formatted using the operating system Format command.
Errors During POST: If the POST detects a problem, an eight-digit error
code is displayed.
Replacing the Default Hard Disk Drive: If you replace the default hard
disk drive, you must recopy all of the files onto the replacement hard
disk drive. To recopy the files:
1. Start the system using the customer's backup copy of the current
system partition.
Warning: This will write over all of the files in the system
partition. Before you do this, you must either have a complete
current backup copy of the system partition or all of the option
diskettes so you can recopy the option files.
2. Select Backup/Restore system programs from the Main Menu.
3. Run Restore System Partition to load the IML image, the system
programs, and the customer and advanced diagnostic programs onto the
system partition.
Notes:
1. If the user's backup copy of the system partition is incomplete, you
will not completely restore the system partition. If this is the
case, after you have recopied the IML image get the option diskettes
and use Copy an option to recopy the option files onto the partition.
2. If the IML image has been loaded onto the hard disk drive but the
customer's operating system has not been loaded, the Insert Diskette
icon will appear on the display.
For information on system programs, see the Diagnostic Information for
Micro Channel Computers pamphlet.
IBM PS/2 Model 90 XP 486 HMR
IML, POST, and BIOS
¦ Copyright IBM Corp. 1990, 1991
1.2.3 - 1
