Intel SE7501WV2 User Manual

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

db  55h, 0AAh, 20h 

; 8KB 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 

Table 66 defines the bitmap for each scan point, indicating when the scan point occurs and 
which resources are available (RAM, stack, binary data area, video, keyboard). 

Near the pointer to the user binary extension structure. The mask bit 
is 0 if this structure is not present. Instead of a jump instruction, the 
scan address (offset 5) contains a 0CB followed by a near pointer. 

01h 

Not applicable 

Not applicable 

Obsolete, no action taken. 

02h 

Not applicable 

Not applicable 

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 number of 
the POST error  

10h Yes 

Yes 

This final scan occurs immediately prior to the INT 19 for normal boot 
and allows one to completely circumvent the normal INT 19 boot if 
desired. 

20h Yes 

Yes 

This scan occurs immediately before the normal option ROM scan.  

40h 

Yes 

Yes 

This scan occurs immediately following the option ROM area scan. 

80h 

Yes 

Yes