Appendix B:
BIOS POST Codes POST Code Description D2h Unknown interrupt D4h Check Intel Branding string D8h Alert Standard Format initialization DEh Log error if micro-code not updated properly The following are for boot block in Flash ROM POST Code Description E0h Initialize the chipset E1h Initialize the bridge E2h Initialize the CPU E3h Initialize system timer E4h Initialize system I/O E5h Check force recovery boot E6h Checksum BIOS ROM E7h Go to BIOS E8h Set Huge Segment E9h Initialize Multi Processor EAh Initialize OEM special code EBh Initialize PIC and DMA ECh Initialize Memory type EDh Initialize Memory size EEh Shadow Boot Block EFh System memory test F0h Initialize interrupt vectors F1h Initialize Run Time Clock F2h Initialize video F3h Initialize System Management Manager F4h Output one beep F5h Clear Huge Segment F6h Boot to Mini DOS F7h Boot to Full DOS * If the BIOS detects errors on 2C, 2E, or 30 (base 512K RAM error), it displays an additional word-bitmap ( xxxx ) indicating the address line or bits that have failed.
For example, “2C 0002” means address line 1 (bit one set) has failed. “2E 1020" means data bits 12 and 5 (bits 12 and 5 set) have failed in the lower 16 bits. The BIOS also sends the bitmap to the port-80 LED display. It first displays the checkpoint code, followed by a delay, the high-order byte, another delay, and then the low-order byte of the error. It repeats this sequence continuously. B-5