81
Chapter 4
23h
1. Check validity of RTC value:
e.g. a value of 5Ah is an invalid value for RTC minute.
2. Load CMOS settings into BIOS stack. If CMOS checksum fails, use default
value
instead.
3. Prepare BIOS resource map for PCI & PnP use. If ESCD is valid, take into
consideration of the ESCD’s legacy information.
4. Onboard clock generator initialization. Disable respective clock resource to
empty PCI
& DIMM slots.
5. Early PCI initialization
-Enumerate PCI bus number
-Assign memory & I/O resource
-Search for a valid VGA device and VGA BIOS, and put it into C000:0
24h
Reserved
25h
Reserved
26h
Reserved
27h
Initialize INT 09 buffer
28h
Reserved
29h
1. Program CPU internal MTRR (P6 & PII) for 0-640K memory address.
2. Initialize the APIC for Pentium class CPU.
3. Program early chipset according to CMOS setup. Example: onboard IDE
controller.
4. Measure CPU speed.
5. Invoke video BIOS.
2Ah
Reserved
2Bh
Reserved
2Ch
Reserved
2Dh
1. Initialize multi-language
2. Put information on screen display, including Award title, CPU type, CPU
speed...
2Eh
Reserved
2Fh
Reserved
30h
Reserved
31h
Reserved
32h
Reserved
33h
Reset keyboard except Winbond 977 series Super I/O chips.
34h
Reserved
35h
Reserved
36h
Reserved
37h
Reserved
38h
Reserved
39h
Reserved
3Ah
Reserved
3Bh
Reserved
.
Checkpoint
Description