Toshiba PORTEGE M400 Maintenance Manual page 69

2.4 System board Troubleshooting
Table 2-3 Debug port (Boot mode) error status (1/10)
D port status
Permission of A20 and Clear of
software reset bit
Prohibition of APIC
Initialization of MCHM, ICHM
Initialization of Super I/O
Initialization of debug port
Dummy read of 3
PIT CH0 initialization
F000h
(for HOLD_ON)
BIOS rewrite factor flag
initialization
CHECK SUM CHECK
EC/KBC rewrite check
F001h
Transition of process to system
BIOS IRT when returned to S3
Key input
Initialization of SC
F002h
BIOS rewrite request check
F006h
Transits to system BIOS IRT
F007h
BIOS rewrite process
PORTEGE M400 Maintenance Manual (960-541)
Inspection items
rd
Bus data
Details
Transition to protected mode
Boot block checksum (skipped when
returned to S3)
Halts when error occurs
Checksum other than boot block (skip
when returned to S3)
If "rewrite" is requested, go to "BIOS rewrite
process"
When a key is pressed, check if it is Tilde
key or Tab key
Halts when error occurs D port=F003h or
04h
If Checksum check error occurred on other
than 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
Transits to real mode and copies BIOS to
RAM
[CONFIDENTIAL]
2 Troubleshooting
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