B-4 Sun Ultra 20 M2 Workstation Service Manual • January 2007
25h Early PCI initialization:
• Enumerate PCI bus number.
• Assign memory and I/O resource.
• Search for a valid VGA device and VGA BIOS, and put it into
C000:0.
26h 1. If Early_Init_Onboard_Generator is not defined, Onboard clock
generator initialization. Disable respective clock resource to empty
PCI and DIMM slots.
2. Init onboard PWM.
3. Init onboard H/W monitor devices.
27h Initialize INT 09 buffer.
28h Reserved.
29h 1. Program CPU internal MTRR (P6 and 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.
2Ah Reserved.
2Bh Invoke video BIOS.
2Ch Reserved.
2Dh 1. Initialize double-byte language font (optional).
2. Put information onscreen display, including award title, CPU
type, CPU speed, and full screen logo.
2Eh Reserved.
2Fh Reserved.
30h Reserved.
31h Reserved.
32h Reserved.
33h Reset keyboard if Early_Reset_KB is defined. For example, Winbond
977 series Super I/O chips. See also POST 63h.
34h Reserved.
35h Test DMA Channel 0.
36h Reserved.
37h Test DMA Channel 1.
TABLE B-1 BIOS Port 80 POST Codes (Continued)
Post Code Description
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