Checkpoint | Description |
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52 | Updates CMOS memory size from memory found in memory test. Allocates memory for |
| Extended BIOS Data Area from base memory. |
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60 | Initializes |
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75 | Initialize |
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78 | Initializes IPL devices controlled by BIOS and option ROMs. |
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7A | Initializes remaining option ROMs. |
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7C | Generate and write contents of ESCD in NVRam. |
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84 | Log errors encountered during POST. |
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85 | Display errors to the user and gets the user response for error. |
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87 | Execute BIOS setup if needed / requested. Check boot password if installed. |
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8C | Late POST initialization of chipset registers. |
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8D | Build ACPI tables (if ACPI is supported) |
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8E | Program the peripheral parameters. Enable/Disable NMI as selected |
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90 | Late POST initialization of system management interrupt. |
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A0 | Check boot password if installed. |
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A1 | |
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A2 | Takes care of runtime image preparation for different BIOS modules. Fill the free area in |
| F000h segment with 0FFh. Initializes the Microsoft IRQ Routing Table. Prepares the |
| runtime language module. Disables the system configuration display if needed. |
|
|
A4 | Initialize runtime language module. Display boot option popup menu. |
|
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A7 | Displays the system configuration screen if enabled. Initialize the CPU??s before boot, |
| which includes the programming of the MTRR??s. |
|
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A8 | Prepare CPU for OS boot including final MTRR values. |
|
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A9 | Wait for user input at config display if needed. |
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AA | Uninstall POST INT1Ch vector and INT09h vector. Deinitializes the ADM module. |
|
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AB | Prepare BBS for Int 19 boot. |
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AC | End of POST initialization of chipset registers. |
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B1 | Save system context for ACPI. |
|
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00 | Passes control to OS Loader (typically INT19h). |
|
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OEM POST Error. This range is reserved for chipset vendors & system manufacturers. The | |
| error associated with this value may be different from one platform to the next. |
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Chapter 4 | 44 |