Toshiba PORTEGE R400 Maintenance Manual page 59

Table 2-4 Debug port (Boot mode) error status (1/10)
D port status
Boot block Permission of A20 and Clear of
software reset bit
Prohibition of APIC
Initialization of MCH and ICH
Initialization of Super I/O
Initialization of debug port
Dummy read of 3rd Bus data
F000H
Only PIT CH0 initialization
(for HOLD_ON)
BIOS rewrite factor flag initialization
CHECK SUM CHECK
F001H
EC/KBC rewrite check
Transition to system BIOS IRT（when
returned to S3)
Key input
When a key is pressed, check if it is
Tilde key or Tab key
F002H
Initialization of SC
F003H
HLT
F004H
HLT
F005H
F006H
BIOS rewrite request check
F007H Transits to System BIOS IRT
BIOS rewrite process
PORTEGE R400 Maintenance Manual (960-623)
Inspection items
2 Troubleshooting Procedures
Details
Transition to protected mode
Boot block checksum (skip when returned to S3)
(halts when error)
Checksum other than boot block (skip when
returned to S3)
If "rewrite" is requested, go to "BIOS rewrite process"
If Checksum check error occurred on except
Boot Block or rewrite is required by user, go to
"BIOS rewrite process".
Initialization of ICHM. D31
DRAM configuration
Permission of cache (L1 cache only)
Memory clear
Transition to real mode and copy of BIOS to
RAM
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