| Power on tests |
CPU synchronizes with
clock. Check the CPU or clock if a failure occurs |
| System ROM Check |
The BIOS runs a checksum
on itself. Check the BIOS chips if a failure occurs |
| DMA controller Fail |
DMA controllers are
initialized and tested. Check the DMA chips if a failure
occurs |
| System Timer Failed |
Channels 0, 1, and
2 are tested in sequence. If a failure occurs, check the
PIT chips |
| Base 64K Memory Testing |
Walking bit test performed
on first 64K of RAM which is critical for the BIOS vector area
to be initialized. Check for bad RAM chips or a bad data
or address line |
| Interrupt Controller
Failed |
Test the 8259 chip |
| CPU Still In Protected
Mode |
Attempts are made to
read the configuration of the system through the 8042 keyboard
controller |
| Refresh Not Occurring |
Memory refresh is tested;
standard refresh is 120-140ns. Check the PIT if a failure
occurs |
| Keyboard Controller
Not Responding |
Tests are run on the
keyboard controller. the the KBC 8042 if a failure occurs |
| Could Not Enter Protected
Mode |
BIOS attempts to enter
protected mode to test extended memory. Check the 8042 KBC
chip or the A20 gate address line if a failure occurs |
| Initialize Timer |
Attempts are made to
initialize the PIT |
| Initialize DMA Controller |
Attempts are made to
initialize the DMA controllers |
| Entering/Exiting Protected
Mode |
The translation is
handled by the keyboard controller and the A20 gate address line.
Check the keyboard controller if a failure occurs |
| Relocate Shadow RAM |
BIOS attempts to shadow
itself into extended memory. Check for memory problems if
a failure occurs |
| Test For EMS |
Check for EMS adapter
or an improper CMOS setting/Jumper setting if a failure occurs |
| Test Video Capabilities |
Normally includes a
memory test on the adapter memory up to 256K |
| Test Memory |
Extensive testing of
Base, Extended,and Expanded memory. Check for defective
memory modules, 8042 KBC, A20 gate address line or an improper
CMOS and/or jumper setting |
| Check System Options |
The hardware in the
system is compared with the values stored in CMOS. The PIT,
PIC, 8042 KBC, RTC and other system board components are tested
again |
| Peripheral Check and
test |
Checks are made for
the peripherals at standard I/O ports including serial and parallel
ports, keyboards, and math coprocessor. You should see
an error message on screen at the point if a failure occurs |
| Floppy Test |
Floppy devices set
in CMOS are checked and initialized. If a bootable floppy
is found the fixed disks are tested and the BIOS will boot to
the floppy disk. Check for defective controllers or an improper
CMOS Setup if a failure occurs |
| Fixed Disk Test |
Checks for fixed disks
in CMOS. If no bootable floppy in the A: drive, then the
BIOS loads the first sector off the first fixed disk and jumps
to the area of memory where the sector was loaded. You may
just see a flashing cursor or an error message from the potential
operating system. Check for improper CMOS Setup, defective
controller, or fixed disk failure. Also, check for a corrupt
bootloader on the fixed disk |
| Advanced Options |
These include the mouse,
cache, etc.. you should see an error message on the screen
at this point, except that a defective cache may hang the system.
In most cases, the cache will be disabled by the BIOS |
