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Appendix B: BIOS POST Codes
B-5
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 rst 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.