VESA BIOS Example

Page 0: Things your program will need

The first thing to do is to set up all the data structures you will need to pass to interrupt 10h. You will also need somewhere to store a list of mode numbers (a list of integers).

Anything after a ';' is a comment. Data description section
The TYPE definitions are not declerations of variables, they are specifications of a structure.
Below them are the declerations.

   TYPE DataBuffer		    ; To be filled by function 00h
      Signature         4 bytes		; 
      VersionL          byte		; lower Version Number
      VersionH          byte		; higher Version Number
      OEMStringPtr      long word	; pointer to description string
      CapableOf         long word	; 32 flags of graphics card capabilities
      VidModePtr        long word	; Pointer to list of available modes
      TotalMemory       word		; Memory available of card
      Reserved          236 bytes	; --
   END TYPE

   TYPE ModeInfoBlock   	    ; To be filled by function 01h
      ModeAttributes      word    	; mode attributes
      WinAAttributes      byte    	; window A attributes
      WinBAttributes      byte    	; window B attributes
      WinGranularity      word    	; window granularity
      WinSize             word    	; window size
      WinASegment         word    	; window A start segment
      WinBSegment         word    	; window B start segment
      WinFuncPtr          long word   ; pointer to window function
      BytesPerScanLine    word    	; bytes per scan line

      XResolution         word    	; horizontal resolution
      YResolution         word    	; vertical resolution
      XCharSize           byte    	; character cell width
      YCharSize           byte    	; character cell height
      NumberOfPlanes      byte    	; number of memory planes
      BitsPerPixel        byte    	; bits per pixel
      NumberOfBanks       byte    	; number of banks
      MemoryModel         byte    	; memory model type
      BankSize            byte    	; bank size in kb
      NumberOfImagePages  byte    	; number of images
      Reserved            byte    	; reserved for page function

      RedMaskSize         byte    	; size of direct color red mask in bits
      RedFieldPosition    byte    	; bit position of LSB of red mask
      GreenMaskSize       byte    	; size of direct color green mask in bits
      GreenFieldPosition  byte    	; bit position of LSB of green mask
      BlueMaskSize        byte    	; size of direct color blue mask in bits
      BlueFieldPosition   byte    	; bit position of LSB of blue mask
      RsvdMaskSize        byte    	; size of direct color reserved mask in bits
      DirectColorModeInfo byte    	; Direct Color mode attributes
      Reserved            216 bytes     ; remainder of ModeInfoBlock
   END TYPE

Next are the Variables. Their declerations follow the format:
Data Type : Variable name

Variables
   DataBuffer : DataBlock 
   ModeInfoBlock : ModeInformation
   Array of 256 words : ModeList