| System Resources | |
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Checkpoint | Description |
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38 | Initializes different devices through DIM. |
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39 | Initializes |
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3A | Initializes RTC date/time. |
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3B | Test for total memory installed in the system. Also, Check for DEL or ESC |
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| keys to limit memory test. Display total memory in the system. |
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3C | Mid POST initialization of chipset registers. |
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40 | Detect different devices (Parallel ports, serial ports, and coprocessor in |
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| CPU…etc.)successfully installed in the system and update the BDA, |
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| EBDA…etc. |
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50 | Programming the memory hole or any kind of implementation that needs |
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| an adjustment in system RAM size if needed. |
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52 | Updates CMOS memory size from memory found in memory test. |
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| 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. |
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8C | Late POST initialization for chipset registers. |
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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 |
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| free area in F000h segment with 0FFh. |
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| Initializes the Microsoft IRQ Routing Table. Prepares the runtime language |
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| module. Disables the system configuration display if needed. |
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A4 | Initialize runtime language module. |
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A7 | Displays the system configuration screen if enabled. Initialize the CPU’s |
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| 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 |
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| module. |
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AB | Prepare BBS for 19 boot. |
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AC | End of POST initialization of chipset registers. |
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B1 | Save system contest for ACPI. |
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00 | Passes control to OS Loader (typically INT19h). |
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