American Megatrends Super Voyager LPX, Руководство пользователя

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Super VGA Functions,
Continued
Super Voyager LPX ISA Motherboard User's Guide
Field Description
08h-0Fh = Reserved, to be defined by VESA
10h-FFh = To be defined by OEM
In version 1.1 and earlier of the VESA SVGA BIOS Extension, Direct
Color 1:5:5:5, 8:8:8, and 8:8:8:8 are defined as Packed Pixel model
with 16, 24, and 32 bits per pixel, respectively. In version 1.2 and later
of the VESA SVGA BIOS Extension, Direct Color modes should use
the Direct Color MemoryModel and use the MaskSize and
FieldPosition fields of the ModeInfoBlock to describe the pixel format.
BitsPerPixel is always defined to be the total size of the pixel in bits.
NumberOfBanks The number of banks in which the scan lines are grouped. The
remainder from dividing the scan line number by the number of banks
is the bank that contains the scan line and the quotient is the scan line
number within the bank. For example, CGA graphics modes have two
banks and Hercules graphics mode has four banks. For modes that do
not have scanline banks (such as VGA modes 0Dh-13h), this field
should be set to 1.
BankSize Specifies the size of a bank (group of scan lines) in units of 1 KB. For
CGA and Hercules graphics modes this is 8, as each bank is 8192 bytes
in length. For modes that do not have scanline banks (such as VGA
modes 0Dh-13h), this field should be set to 0.
NumberOfImagePages Specifies the number of additional complete display images that will fit
into the VGA's memory, at one time, in this mode. The application may
load more than one image into the VGA's memory if this field is non-
zero, and flip the display between the images.
Reserved Supports a future VESA BIOS extension feature and will always be set
to one in this version.
RedMaskSize,
GreenMaskSize,
BlueMaskSize,
RsvdMaskSize
Define the size, in bits, of the red, green, and blue components of a
direct color pixel. A bit mask can be constructed from the MaskSize
fields using simple shift arithmetic. Example MaskSize values for
Direct Color 5:6:5 mode would be 5, 6, 5, and 0, for the red, green,
blue, and reserved fields, respectively. The MaskSize field should be set
to 0 in modes using a MemoryModel that does not have pixels with
component fields.
The RedFieldPosition, GreenFieldPosition, BlueFieldPosition, and
RsvdFieldPosition fields define the bit position within the direct color
pixel or YUV pixel of the least significant bit of the respective color
component. A color value can be aligned with its pixel field by shifting
the value left by the FieldPosition. Example FieldPosition values for
Direct Color 5:6:5 mode would be 11, 5, 0, and 0, for the red, green,
blue, and reserved fields, respectively. The FieldPosition fields should
be set to 0 in modes using a MemoryModel that does not have pixels
with component fields.
DirectColorModeInfo Describes important characteristics of direct color modes. Bit 0
specifies if the color ramp of the DAC is fixed or programmable. If the
color ramp is programmable, the red, green, and blue lookup tables can
be loaded using a standard VGA DAC color registers BIOS call (AX =
1012h). Bit 1 specifies if the Rsvd field of the direct color pixel can be
used.