Toshiba Portege R500 Maintenance Manual - Page 65

2.4 System Board Troubleshooting 2 Troubleshooting Procedures Table 2-5 Debug port (Boot mode) error status (1/10) D port status Inspection items 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 Details F000H F001H Dummy read of 3rd Bus data Only PIT CH0 initialization (for HOLD_ON) BIOS rewrite factor flag initialization CHECK SUM CHECK EC/KBC rewrite check 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" F002H F005H F006H F007H F008H F009H 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 Initialization of SC BIOS rewrite request check BIOS signature check Transits to System BIOS IRT 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 PORTEGE R500 Maintenance Manual (960-634) [CONFIDENTIAL] 2-19