68
Chapter 5
Additional BUS Checkpoints
While control is in the BUS routines, additional checkpoints are ouput to
I/O port address 0080h as word to identify the routines being executed.
These are word checkpoints. The low byte of checkpoint is the system
BIOS checkpoint where control is passed to the different BUS rou-
tines. The high byte of checkpoint indicates that the routine is being
executed in different BUSes.
The high byte of these checkpoints includes the following information:
Beep Codes
Fatal errors, which halt the boot process, are communicated through a
series of audible beeps. If AMIBIOS POST can initialize the system
video display, it displays the error message. Displayed error messages,
in most cases, allow the system to continue to boot. Displayed error
messages are described on pages 68-69. See the top of the next page
for the beep code chart.
Bits
Description
Bits 7-4
0000
Function 0. Disable all devices on the bus.
0001
Function 1. Initialize static devices on the bus.
0010
Function 2. Initialize output devices on the bus.
0011
Function 3. Initialize input devices on the bus.
0100
Function 4. Initialize IPL devices on the bus.
0101
Function 5. Initiate general devices on the bus.
0110
Function 6. Initialize error reporting on the bus.
0111
Function 7. Initialize add-on ROMs for all buses.
Bits 3-0
Specify the bus
0
Generic DIM Device Initialization Manager.
1
Onboard System devices.
2
ISA devices.
3
EISA devices.
4
ISA PnP devices.
5
PCI devices.
