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2.4 System Board Troubleshooting 2 Troubleshooting Procedures
Table 2-5 Printer port LED status (1/8)
LED Status Test item Contents
Start Permission of A20 and Clear of software reset bit
Prohibition of APIC
Initialization of MCHM
Initialization of ICHM
Initialization of Super I/O
Initialization of debug port
Dummy read of 3
rd
Bus data
Setting of printer port
B0h Flash ROM check PIT CH0 initialization (for HOLD_ON)
BIOS rewrite factor flag initialization
CHECK SUM CHECK
Transition to protected mode
Boot block checksum (skip when returned to S3)
The program halts when checksum error
occurred.
Checksum other than boot block (skip when
returned to S3)
EC/KBC rewrite check
B1h KBC initialization
If “rewrite” is requested, go to “BIOS rewrite
process”.
Transition of process to System BIOS IRT when
returned to S3)
Key input
Check of Tilde key ( key) and Tab key if a key
is pressed
B2h BIOS rewrite request check BIOS rewrite request check if Checksum check
error occurred on except Boot Block or rewrite is
required by user. “BIOS rewrite process”.
Transits to System BIOS IRT.
Initialization of ICHM. D31
DRAM configuration
Permission of cache (L1 cache only)
Memory clear
B3h BIOS rewrite (1)
Transition to real mode and copy of BIOS to RAM
B5h
Saving of key scan code
Initialization of TASK_1ms_TSC setting screen
B6h BIOS rewrite
FAN control
Sound initialization (for BEEP sound)
System speaker enable
Satellite A40 Maintenance Manual (960-458) 2-23