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Format of SuperVGA information

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Offset Size Description

00h

4 BYTEs

(ret) signature ("VESA")
(call) VESA 2.0 request signature ("VBE2"), required to receive version 2.0 info

04h

WORD

VESA version number (one-digit minor version -- 0102h = v1.2)

06h

DWORD

pointer to OEM name
"761295520" for ATI

0Ah

DWORD

capabilities flags (see #00078)

0Eh

DWORD

pointer to list of supported VESA and OEM video modes (list of words terminated with FFFFh)

12h

WORD

total amount of video memory in 64K blocks
VBE v1.x

14h

236 BYTEs

reserved
VBE v2.0

14h

WORD

OEM software version (BCD, high byte = major, low byte = minor)

16h

DWORD

pointer to vendor name

1Ah

DWORD

pointer to product name

1Eh

DWORD

pointer to product revision string

22h

WORD

(if capabilities bit 3 set) VBE/AF version (BCD) 0100h for v1.0P

24h

DWORD

(if capabilities bit 3 set) pointer to list of supported accelerated video modes (list of words terminated with FFFFh)

28h

216 BYTEs

reserved for VBE implementation

100h

256 BYTEs

OEM scratchpad (for OEM strings, etc.)

Note:

The list of supported video modes is stored in the reserved portion of the SuperVGA information record by some implementations, and it may thus be necessary to either copy the mode list or use a different buffer for all subsequent VESA calls.
Not all of the video modes in the list of mode numbers may be supported, e.g. if they require more memory than currently installed or are not supported by the attached monitor. Check any mode you intend to use through AX=4F01h first.
The 1.1 VESA document specifies 242 reserved bytes at the end, so the buffer should be 262 bytes to ensure that it is not overrun; for v2.0, the buffer should be 512 bytes.
The S3 specific video modes will most likely follow the FFFFh terminator at the end of the standard modes. A search must then be made to find them, FFFFh will also terminate this second list.
In some cases, only a "stub" VBE may be present, supporting only AX=4F00h; this case may be assumed if the list of supported video modes is empty (consisting of a single word of FFFFh).