Intel 4.5.2.2Scan Point Definitions, Basic Input Output System BIOS, STL2 Server Board TPS

Basic Input Output System (BIOS) STL2 Server Board TPS

The following code fragment shows the header and format for a user binary:

	db	55h, 0AAh, 20h	; 16KB USER Area
MyCode	PROC	FAR	; MUST be a FAR procedure
	db	CBh	; Far return instruction
	db	04h	; Bit map to define call points, a 1
			; in any bit specifies
			; that the BIOS is called at that
			; scan point in POST
	db	CBh	; First transfer address used to
			; point to user binary extension
			; structure
	dw	?	; Word Pointer to extension
			; structure
	dw	0	; Reserved
	JMP	ErrRet	; This is a list of 7 transfer
			; addresses, one for each
	JMP	ErrRet	; bit in the bitmap.
			; 5 Bytes must be used for each
	JMP	Start	; JMP to maintain proper offset for
			; each entry. Unused entry JMP’s
			; should be filled with 5 byte
			; filler or JMP to a RETF
	JMP	ErrRet	;
	JMP	ErrRet
	JMP	ErrRet
	JMP	ErrRet

4.5.2.2Scan Point Definitions

The table below defines the bitmap for each scan point, indicating when the scan point occurs and which resources are available (RAM, stack, binary data area, video, and keyboard).

Table 4-21. User Binary Area Scan Point Definitions

Scan Point	Mask	RAM/Stack/BDA	Video/Keyboard
Near pointer to the user binary extension structure, mask bit is 0 if	01h	Not applicable	Not applicable
this structure is not present. Instead of a jump instruction the scan
address (offset 5) contains an 0CB followed by a near pointer.
Obsolete. No action taken.	02h	NA	NA
This scan occurs immediately after video initialization.	04h	Yes	Yes
This scan occurs immediately before video initialization.	08h	Yes	No
This scan occurs on POST error. On entry, BX contains the	10h	Yes	Yes
number of the POST error.
This final scan occurs immediately prior to the INT 19 for normal	20h	Yes	Yes
boot and allows one to completely circumvent the normal INT 19
boot if desired.
This scan occurs immediately before the normal option ROM	40h	Yes	Yes
scan.
This scan occurs immediately following the option ROM area	80h	Yes	Yes

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