Toshiba PORTEGE R300 Maintenance Manual page 67

Table 2-4-1 Debug port (Boot mode) error status (1/9)
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
Setting of printer port
F000H
BTBK_START
Only PIT CH0 initialization
(for HOLD_ON)
BIOS rewrite factor flag initialization
CHECK SUM CHECK
F001H BTBK_CALC_CHKSUM_END
EC/KBC rewrite check
Key input
When a key is pressed, check if it is
Tilde key or Tab key
F002H BTBK_INI_SC_START
Initialization of SC
F003H
BTBK_INI_SC_ERR
F004H BTBK_SC_HW_FAILURE
F005H
Enables CPU cache
F006
BTBk_INT_TPM
BIOS rewrite request check
F007 BTBK_ENTER_CHK_BIOS_SIGN
BIOS signature check
F008H BTBK_ENTER_SYSTEM_BIOS
Transits to System BIOS IRT
BIOS rewrite process
PORTEGE R300 Maintenance Manual (960-591)
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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
[CONFIDENTIAL] 2-25