| Appendix B: BIOS POST Codes  | 
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POST Code | Description | 
5Ch  | Test RAM between 512 and 640 kB  | 
60h  | Test extended memory  | 
62h  | Test extended memory address lines  | 
64h  | Jump to UserPatch1  | 
66h  | Confi gure advanced cache registers  | 
67h  | Initialize Multi Processor APIC  | 
68h  | Enable external and CPU caches  | 
69h  | Setup System Management Mode (SMM) area  | 
6Ah  | Display external L2 cache size  | 
6Bh  | Load custom defaults (optional)  | 
6Ch  | Display   | 
70h  | Display error messages  | 
72h  | Check for confi guration errors  | 
76h  | Check for keyboard errors  | 
7Ch  | Set up hardware interrupt vectors  | 
7Dh  | Initialize Intelligent System Monitoring (optional)  | 
7Eh  | Initialize coprocessor if present  | 
80h  | Disable onboard Super I/O ports and IRQs (optional)  | 
81h  | Late POST device initialization  | 
82h  | Detect and install external RS232 ports  | 
83h  | Confi gure   | 
84h  | Detect and install external parallel ports  | 
85h  | Initialize   | 
86h  | |
87h  | Confi gure Motherboard Confi gurable Devices  | 
  | (optional)  | 
88h  | Initialize BIOS Data Area  | 
89h  | Enable   | 
8Ah  | Initialize Extended BIOS Data Area  | 
8Bh  | Test and initialize PS/2 mouse  | 
8Ch  | Initialize fl oppy controller  | 
8Fh  | Determine number of ATA drives (optional)  | 
90h  | Initialize   | 
91h  | Initialize   | 
92h  | Jump to UserPatch2  | 
93h  | Build MPTABLE for   | 
95h  | Install CD ROM for boot  | 
96h  | Clear huge ES segment register  | 
97h  | Fix up Multi Processor table  | 
98h  | |
  | long, two short beeps on checksum failure  |