Introduction
22
English
21h
HPM initialization (notebook platform)
22h
Reserved
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 & VGA BIOS, and put it into C000:0.
24-26h
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.
2A-2Ch
Reserved
2Dh
1. Initialize multi-language
2. Put information on screen display, including Award title, CPU type, CPU speed ….
2E-32h
Reserved
33h
Reset keyboard except Winbond 977 series Super I/O chips.
34-3Bh
Reserved
3Ch
Test 8254
3Dh
Reserved
3Eh
Test 8259 interrupt mask bits for channel 1.
3Fh
Reserved
40h
Test 8259 interrupt mask bits for channel 2.
41h
Reserved
42h
Reserved
43h
Test 8259 functionality.
44h
Reserved
45-46h
Reserved
47h
Initialize EISA slot
48h
Reserved
49h
1. Calculate total memory by testing the last double word of each 64K page.
2. Program writes allocation for AMD K5 CPU.
4A-4Dh
Reserved
4Eh
1. Program MTRR of M1 CPU
2. Initialize L2 cache for P6 class CPU & program CPU with proper cacheable range.
3. Initialize the APIC for P6 class CPU.
4. On MP platform, adjust the cacheable range to smaller one in case the cacheable
ranges between each CPU are not identical.
4Fh
Reserved
50h
Initialize USB
51h
Reserved
52h
Test all memory (clear all extended memory to 0)
53-54h
Reserved
55h
Display number of processors (multi-processor platform)
56h
Reserved
57h
1. Display PnP logo
2. Early ISA PnP initialization
