Toshiba PORTEGE A200 series Maintenance Manual page 61

2 Troubleshooting Procedures
D port
Status
Clears software rest bit.
Permits A20 line.
Initializes special register and Intel chipset.
F000h 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.
F001h
Checks rewriting EC/KBC? Goes to BIOS rewriting process at request for
rewriting.
Executes KBC initializing sequence.
Transmits KBC enable command.
Checks F12 key.
F002h
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).
Memory clear
2-20
Table 2-5 Debugging port status (1/7)
2.4 System Board Troubleshooting
Contents
PORTEGE A200 Maintenance Manual (960-499)