Bus Initialization Checkpoints; Upper Nibble High Byte Functions - Intel BLKD865GSAL Technical Product Specification

Table 49. Runtime Code Uncompressed in F000 Shadow RAM (continued)
Code Description of POST Operation
AE Uncompress SMBIOS module and init SMBIOS code and form the runtime SMBIOS image in
shadow.
B1 Going to copy any code to specific area.
00 Copying of code to specific area done. Going to give control to INT-19 boot loader.
4.3

Bus Initialization Checkpoints

The system BIOS gives control to the different buses at several checkpoints to do
various tasks. Table 50 describes the bus initialization checkpoints.
Table 50. Bus Initialization Checkpoints
Checkpoint Description
2A Different buses init (system, static, and output devices) to start if present.
38 Different buses init (input, IPL, and general devices) to start if present.
39 Display different buses initialization error messages.
95 Init of different buses optional ROMs from C800 to start.
While control is inside the different bus routines, additional checkpoints are output to
port 80h as WORD to identify the routines under execution. In these WORD
checkpoints, the low byte of the checkpoint is the system BIOS checkpoint from which
the control is passed to the different bus routines. The high byte of the checkpoint is
the indication of which routine is being executed in the different buses. Table 51
describes the upper nibble of the high byte and indicates the function that is being
executed.
Table 51. Upper Nibble High Byte Functions
Value Description
0 func#0, disable all devices on the bus concerned.
1 func#1, static devices init on the bus concerned.
2 func#2, output device init on the bus concerned.
3 func#3, input device init on the bus concerned.
4 func#4, IPL device init on the bus concerned.
5 func#5, general device init on the bus concerned.
6 func#6, error reporting for the bus concerned.
7 func#7, add-on ROM init for all buses.
Error Messages and Beep Codes
91