| Appendix |
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Appendix B
B-1 POST CODES
ISA POST codes are typically output to I/O port address 80h.
POST (hex) | DESCRIPTION |
Reserved. | |
C0 | Turn off OEM specific cache, shadow. |
031. Initialize EISA registers (EISA BIOS only).
2. Initialize all the standard devices with default values Standard devices includes.
- DMA controller (8237).
- Programmable Interrupt Controller (8259).
| - Programmable Interval Timer (8254). | |
| - | RTC chip. |
04 | Reserved | |
05 | 1. | Keyboard Controller |
06 | 2. | Enable Keyboard Interface. |
07 | Reserved. | |
08 | Verifies CMOS's basic R/W functionality. | |
C1 | ||
C5 | Copy the BIOS from ROM into | |
| so that POST will go faster. | |
08 | Test the first 256K DRAM. | |
09 | OEM specific cache initialization. (if needed) | |
0A | 1. | Initialize the first 32 interrupt vectors with correspond |
| ing Interrupt handlers. Initialize INT numbers from | |
| with Dummy (Spurious) Interrupt Handler. | |
| 2. | Issue CPUID instruction to identify CPU type. |
| 3. | Early Power Management initialization. (OEM specific) |
0B | 1. | Verify the RTC time is valid or not. |
| 2. | Detect bad battery. |
| 3. | Read CMOS data into BIOS stack area. |
| 4. | PnP initializations including. (PnP BIOS only) |
- Assign CSN to PnP ISA card.