Acer Aspire ZS600, Service Manual

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Troubleshooting
4-7
Bootblock Recovery Code Checkpoints
0
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.
NOTE: NOTE :
Checkpoints may differ between different platforms based on system configuration.
Checkpoints may change due to vendor requirements, system chipset or option ROMs
from add-in PCI devices
D5 Bootblock code is copied from ROM to lower system memory and control
is given to it. BIOS now executes out of RAM. Copies compressed boot
block code to memory in right segments. Copies BIOS from ROM to RAM
for faster access. Performs main BIOS checksum and updates recovery
status accordingly.
D6 Both key sequence and OEM specific method is checked to determine if
BIOSrecovery is forced. Main BIOS checksum is tested. If BIOS
recovery is necessary,control flows to checkpoint E0. See Bootblock
Recovery Code Checkpoints sectionfor more information.
D7 Restore CPUID value back into register. The Bootblock-Runtime
interface module is moved to system memory and control is given to it.
Determine whether to execute serial flash.
D8 The Runtime module is uncompressed into memory. CPUID information
is stored in memory.
D9 Store the Uncompressed pointer for future use in PMM. Copying Main
BIOS into memory. Leaves all RAM below 1MB Read-Write including
E000 and F000 shadow areas but closing SMRAM.
DA Restore CPUID value back into register. Give control to BIOS POST
(ExecutePOSTKernel).See POST Code Checkpoints section of document
for more information.
DC System is waking from ACPI S3 state.
E1-E8 ECEE OEM memory detection/configuration error. This range is reserved for
chipset vendors & system manufacturers. The error associated with this
value may be different from one platform to the next.
Table 4-2.
Checkpoint Description