Intel Raptor AT manual Post Checkpoint Codes, Checkpoint Description Code

Appendix D: Industrial Devices

POST Checkpoint Codes

When AMIBIOS performs the Power On Self Test, it writes diagnostic codes checkpoint codes to I/O port 0080h where the POST code display is connected.

Table D-4 Uncompressed Initialization Codes

The uncompressed initialization checkpoint codes are listed in order of execution:

Checkpoint	Description
Code
D0h	The NMI is disabled. Power on delay is starting. Next,
	the initialization code checksum will be verified.
	Initializing the DMA controller, performing the
D1h	keyboard controller BAT test, starting memory refresh,
	and entering 4 GB flat mode next.
D3h	Starting memory sizing next.
D4h	Returning to real mode. Executing any OEM patches
	and setting the stack next.
	Passing control to the uncompressed code in shadow
D5h	RAM at E000:0000h.The initialization code is copied to
	segment 0 and control will be transferred to segment 0.
	Control is in segment 0. Next, checking if <Ctrl>
	<Home> was pressed and verifying the system BIOS
	checksum.
D6h	If either <Ctrl> <Home> was pressed or the system
	BIOS checksum is bad, next will go to checkpoint code
	E0h.
	Otherwise, going to checkpoint code D7h.
D7h	Main BIOS runtime code is to be decompressed and
	control to be passed to main BIOS in shadow RAM.

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