2 Troubleshooting Procedures 2.5 FDD TroubleshootingSystem Board Troubleshooting Table 2-3 Printer port LED boot mode status (1/8) LED Status Test item Message
Register initialization for boot block
Clearance of software reset bit
Permission of A20 line
FFh Start
Initialization for special register and Intel chip set
PIT CH0 initialization (for HOLD_ON)
BIOS rewrite flag initialization
Checksum check
Transition to protected mode
Boot block checksum (HLT when check error occurred.)
B0H Flash ROM check
Checksum check except boot block
Transition to BIOS rewriting when required
Enabling KB
B1H EC/KBC rewrite check
[tilde] [TAB] key check
B2H BIOS rewrite request check Transition to BIOS rewriting when checksum error other
than Boot Block is detected, or user requested rewriting.
System BIOS rewrite transition to
IRT
Rewriting BIOS
Setting of base for Power Management I/O Space
Enabling BIOS writing
Serial interrupt control
Disabling BIOS rewrite protection
Enabling SM Bus I/O space
Enabling SM Bus access
Opening work I/O for SDRAM initialization
H/W initialization
Setting FDC prohibition
Initialization of HW for each model
Initialization of PIT channel 1
(Setting refresh interval to 30ms)
Initialization of PIT, DMAC, PIC
DRAM configuration
Enabling L1 cache
Memory clear
B3H
Transition to real mode, copy BIOS
to RAM