Gigabyte Gag1975xc Manual
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Appendix - 101 -
English4-3 POST Error Code
POST (hex)Description
CFh Test CMOS R/W functionality
C0h Early chipset initialization:
- Disable shadow RAM
- Disable L2 cache (socket 7 or below)
- Program basic chipset registers
C1h 1. Detect memory
- Auto-detection of DRAM size, type and ECC
- Auto-detection of L2 cache (socket 7 or below)
2. PEG slots Auto-Configuration
C3h Expand compressed BIOS code to DRAM
C5h Call chipset hook to copy BIOS back to E000 & F000 shadow RAM
0h1 Expand the Xgroup codes locating in physical address 1000:0
03h Initial Superio_Early_Init switch
05h 1. Blank out screen
2. Clear CMOS error flag
07h 1. Clear 8042 interface
2. Initialize 8042 self-test
08h 1. Test special keyboard controller for Winbond 977 series Super I/O chips
2. Enable keyboard interface.
0Ah 1. Disable PS/2 mouse interface (optional)
2. Auto detect ports for keyboard & mouse followed by a port &
interface swap (optional)
3. Reset keyboard for Winbond 977 series Super I/O chips
0Eh Test F000h segment shadow to see whether it is R/W-able or not.
If test fails, keep beeping the speaker
10h Auto detect flash type to load appropriate flash R/W codes into the
run time area in F000 for ESCD & DMI support.
12h Use walking 1s algorithm to check out interface in CMOS circuitry.
Also set real-time clock power status, and then check for override.
14h Program chipset default values into chipset. Chipset default values are
MODBINable by OEM customers.
16h Initial Early_Init_Onboard_Generator switch
18h Detect CPU information including brand, SMI type (Cyrix or Intel) and
CPU level (586 or 686)
1Bh Initial interrupts vector table. If no special specified, all H/W interrupts
are directed to SPURIOUS_INT_HDLR & S/W interrupts to
SPURIOUS_soft_HDLR.
GA-G1975X-C Motherboard - 102 -
English
POST (hex)Description
1Dh Initial EARLY_PM_INIT switch
1Fh Load keyboard matrix (notebook platform)
21h HPM initialization (notebook platform)
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 ESCDs 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
25h PCI Bus Initialization
26h Init clock Generator
27h Initialize INT 09 buffer
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
2Bh Invoke video BIOS
2Dh 1. Initialize multi-language
2. Put information on screen display, including Award title, CPU type,
CPU speed...
33h Reset keyboard except Winbond 977 series Super I/O chips
3Ch Test 8254
3Eh Test 8259 interrupt mask bits for channel 1
40h Test 8259 interrupt mask bits for channel 2
43h Test 8259 functionality
47h Initialize EISA slot
49h 1. Calculate total memory by testing the last double word of each 64K page
2. Program write allocation for AMD K5 CPU 64K page
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
Appendix - 103 -
English POST (hex)Description
50h Initialize USB
52h Test all memory (clear all extended memory to 0)
55h Display number of processors (multi-processor platform)
57h 1. Display PnP logo
2. Early ISA PnP initialization
- Assign CSN to every ISA PnP device
59h Initialize the combined Trend Anti-Virus code
5Bh (Optional Feature)
Show message for entering AWDFLASH.EXE from FDD (optional)
5Dh 1. Initialize Init_Onboard_Super_IO switch
2. Initialize Init_Onbaord_AUDIO switch
60h Okay to enter Setup utility; i.e. not until this POST stage can users
enter the CMOS setup utility
65h Initialize PS/2 Mouse
67h Prepare memory size information for function call:
INT 15h ax=E820h
69h Turn on L2 cache
6Bh Program chipset registers according to items described in Setup &
Auto-configuration table
6Dh 1. Assign resources to all ISA PnP devices
2. Auto assign ports to onboard COM ports if the corresponding item in
Setup is set to AUTO
6Fh 1. Initialize floppy controller
2. Set up floppy related fields in 40:hardware
73h (Optional Feature)
Enter AWDFLASH.EXE if :
- AWDFLASH is found in floppy drive
- ALT+F2 is pressed
75h Detect & install all IDE devices: HDD, LS120, ZIP, CDROM...
77h Detect serial ports & parallel ports
7Ah Detect & install co-processor
7Fh 1. Switch back to text mode if full screen logo is supported
- If errors occur, report errors & wait for keys
- If no errors occur or F1 key is pressed to continue:
GA-G1975X-C Motherboard - 104 - English POST (hex)Description 82h 1. Call chipset power management hook 2. Recover the text fond used by EPA logo (not for full screen logo) 3. If password is set, ask for password 83h Save all data in stack back to CMOS 84h Initialize ISA PnP boot devices 85h 1. USB final Initialization 2. NET PC: Build SYSID structure 3. Switch screen back to text mode 4. Set up ACPI table at top of memory 5. Invoke ISA adapter ROMs 6. Assign IRQs to PCI devices 7. Initialize APM 8. Clear noise of IRQs 93h Read HDD boot sector information for Trend Anti-Virus code 94h 1. Enable L2 cache 2. Program boot up speed 3. Chipset final initialization 4. Power management final initialization 5. Clear screen & display summary table 6. Program K6 write allocation 7. Program P6 class write combining 95h 1. Program daylight saving 2. Update keyboard LED & typematic rate 96h 1. Build MP table 2. Build & update ESCD 3. Set CMOS century to 20h or 19h 4. Load CMOS time into DOS timer tick 5. Build MSIRQ routing table FFh Boot attempt (INT 19h)