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2 Troubleshooting Procedures 2.4 System Board Troubleshooting
2-20 PORTEGE A200 Maintenance Manual (960-499)
Table 2-5 Debugging port status (1/7)
Clears software rest bit.
Permits A20 line.
Initializes special register and Intel chipset.
Initializes PIT CH0 only (for HOLD_ON).
Initializes flag of factor rewriting of BIOS.
Checks CHECK SUM.
Transition to protect mode.
Calculates the checksum of Boot block? HLT at checksum error
Calculates the checksum of block other than Boot block.
Checks rewriting EC/KBC? Goes to BIOS rewriting process at request for
Executes KBC initializing sequence.
Transmits KBC enable command.
Checks F12 key.
Checks for request of BIOS rewriting? Checksum error of blocks other than
BootBlock, at the request of F12 rewriting request.
F003h Transfers the process to the System BIOS IRT side.
BIOS rewriting process
Initializes peculiar HW to the model.
Initializes GPIO I/O space.
Permits BIOS writing.
Controls serial interrupts.
Releases the write-protect of BIOS.
Permits the SMBus I/O space.
Permits the access to SMBus.
Configuration of DRAM
Permits cache (only L1 Cache).