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Chapter 4 42
Bootblock Recovery Code Checkpoints
POST Code Checkpoints
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.
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."
07 Fixes CPU POST interface calling pointer.
08 Initializes the CPU. The BAT test is being done on KBC. Program the keyboard controller
command byte is being done after Auto detection of KB/MS using AMI KB-5.