Acer AC100, Руководство по обслуживанию

Страница: 103 / 112

Chapter 8 97
Bootblock recovery code checkpoints
The Bootblock recovery code gets control when the BIOS determines that a BIOS recovery needs to occur
because the user has forced the update or the BIOS checksum is corrupt. The following table describes the
type of checkpoints that may occur during the Bootblock recovery portion of the BIOS:
POST code checkpoints
The POST code checkpoints are the largest set of checkpoints during the BIOS pre-boot process. The
following table describes the type of checkpoints that may occur during the POST portion of the BIOS:
Checkpoint Description
E0 Initialize the floppy controller in the super I/O. Some interrupt vectors are initialized.
DMA controller is initialized. 8259 interrupt controller is initialized. L1 cache is
enabled.
E9 Set up floppy controller and data. Attempt to read from floppy.
EA Enable ATAPI hardware. Attempt to read from ARMD and ATAPI CDROM.
EB Disable ATAPI hardware. Jump back to checkpoint E9.
EF Read error occurred on media. Jump back to checkpoint EB.
E9 no EA Determine information about root directory of recovery media.
F0 Search for pre-defined recovery file name in root directory.
F1 Recovery file not found.
F2 Start reading FAT table and analyze FAT to find the clusters occupied by the recovery
file.
F3 Start reading the recovery file cluster by cluster.
F5 Disable L1 cache.
FA Check the validity of the recovery file configuration to the current configuration of the
flash part.
FB Make flash write enabled through chipset and OEM specific method. Detect proper
flash part. Verify that the found flash part size equals the recovery file size.
F4 The recovery file size does not equal the found flash part size.
FC Erase the flash part.
FD Program the flash part.
FF The flash has been updated successfully. Make flash write disabled. Disable ATAPI
hardware. Restore CPUID value back into register. Give control to F000 ROM at
F000:FFF0h.
Checkpoint Description
03 Disable NMI, Parity, video for EGA, and DMA controllers. Initialize BIOS, POST,
Runtime data area. Also initialize BIOS modules on POST entry and GPNV area.
Initialized CMOS as mentioned in the Kernel Variable "wCMOSFlags."
04 Check CMOS diagnostic byte to determine if battery power is OK and CMOS
checksum is OK. Verify CMOS checksum manually by reading storage area. If the
CMOS checksum is bad, update CMOS with power-on default values and clear
passwords. Initialize status register A.
Initializes data variables that are based on CMOS setup questions. Initializes both
the 8259 compatible PICs in the system.
05 Initializes the interrupt controlling hardware (generally PIC) and interrupt vector table.
06 Do R/W test to CH-2 count reg. Initialize CH-0 as system timer. Install the
POSTINT1Ch handler. Enable IRQ-0 in PIC for system timer interrupt.
Traps INT1Ch vector to "POSTINT1ChHandlerBlock."