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Super VGA Functions,
Continued
Chapter 4 VGA BIOS
124
Field Description
1 Window is writeable
Bit 1 Window readable
0
Window is not readable
1 Window is readable
Bit 0 Windows supported
0
Window is not supported
1 Window is supported
If neither window is supported (bit 0 is 0), window paging is not
supported and the display memory buffer resides at the CPU address
appropriate for the MemoryModel of the mode.
WinGranularity Specifies the smallest boundary, in KB, on which the window can be
placed in the video memory. If WinGranularity equals zero then CPU
display memory windowing is not supported.
WinSize Specifies the size of the window in KB.
WinASegment
WinBSegment Specify the segment addresses where the windows are located in the
CPU address space.
WinFuncAddr Specifies the address of the CPU video memory windowing function.
The windowing function can be invoked either through SVGA INT 10h
function 05h, or by calling the function directly. A direct call will
provide faster access to the hardware paging registers than using INT
10h and is to be used by high performance applications. If WinFuncPtr
is NULL (0000:0000) then CPU display memory windowing is not
supported.
XResolution
YResolution Specify the width and height of the video mode. In graphics modes, this
resolution is in units of pixels. In text modes this resolution is in units
of characters. Note that text mode resolutions, in units of pixels, can be
obtained by multiplying XResolution and YResolution by the cell width
and height, if the extended information is present.
XCharSize
YCharSize Specify the size of the character cell in pixels.
NumberOfPlanes Specifies the number of memory planes available to software in that
mode. For standard 16-color VGA graphics, this would be set to 4. For
standard packed pixel modes, the field would be set to 1.
BitsPerPixel Specifies the number of bits that define the color of one pixel. For
example, a standard VGA four-plane 16-color graphics mode would
have a 4 in this field and a packed pixel 256-color graphics mode would
specify 8 in this field. The number of bits per pixel per plane can
normally be derived by dividing the BitsPerPixel field by the
NumberOfPlanes field.
MemoryModel Specifies the general type of memory organization used in this mode.
The following models have been defined:
00h = Text mode
01h = CGA graphics
02h = Hercules graphics
03h = 4-plane planar
04h = Packed pixel
05h = Non-chain 4, 256 color
06h = Direct color
07h = YUV