Award BIOS logo

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  | The image data; a series of rows of pixels.
* In the 4-bit variant, each row of pixels is stored as four bitmaps, each storing one bit of the pixel value, starting with the least significant bit. Within each bitmap, pixels are stored left-to-right, and the most significant bit is the leftmost one. There is no information available on how the format is supposed to behave for image widths that are not multiples of 8 bits.
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* In the 4-bit variant, each row of pixels is stored as four bitmaps, each storing one bit of the pixel values, starting with the bitmap for the least significant bit. Within each bitmap, pixels are stored left-to-right, and the most significant bit is the leftmost one. There is no information available on how the format is supposed to behave for image widths that are not multiples of 8 bits.
 
* In the 8-bit variant, this is simply an array of pixel values, stored row-by-row, left-to-right.
 
* In the 8-bit variant, this is simply an array of pixel values, stored row-by-row, left-to-right.
 
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Revision as of 20:34, 10 March 2015

File Format
Name Award BIOS logo
Ontology
Extension(s) .epa, .bmp

Award BIOS logo (also known as EPA or AWBM) is a family of image formats associated with Award BIOS firmware. These formats are used by those who wish to change the image shown on the boot screen of certain computers. The default image is usually an "Energy Star" logo.

Contents

Format

There are at least two main versions of the format, sometimes called "version 1" and "version 2". Additionally, different versions of the BIOS have different restrictions on the size of the image, etc. There is evidence that different BIOS versions may even render the same file differently.

Version 1

Version 1 images are rendered in text mode, by customizing the character graphics. Consequently, each 8×14 cell of pixels can only use two different colors.

There is no identifying signature, but most files begin with 0x11 0x06 or 0x11 0x09, based on the usual dimensions of the image in cells.

There are usually two images in the file, the second being the small blue Award logo that also appears on the boot screen.

Version 2

Version 2 files begin with a signature of "AWBM". This is a more typical kind of image format, not based on character graphics. It appears in two variants: "semi-planar 4-bit" and "packed 8-bit".

All values are little-endian.

Name Length and type Description
4-bit variant 8-bit variant
magic 4 bytes Always equal to 'A' 'W' 'B' 'M' (i.e. 41 57 42 4d)
width uint16_t Image width and height in pixels. Common image dimensions include 136x84, 136x126 and 640x480.
height uint16_t
data width × height / 2 bytes width × height bytes The image data; a series of rows of pixels.
  • In the 4-bit variant, each row of pixels is stored as four bitmaps, each storing one bit of the pixel values, starting with the bitmap for the least significant bit. Within each bitmap, pixels are stored left-to-right, and the most significant bit is the leftmost one. There is no information available on how the format is supposed to behave for image widths that are not multiples of 8 bits.
  • In the 8-bit variant, this is simply an array of pixel values, stored row-by-row, left-to-right.
palmagic 4 bytes Always equal to 'R' 'G' 'B' ' ' (i.e. 52 47 42 20).
paldata 16 × 3 bytes 256 × 3 bytes EGA palette data: an array of triplets of bytes in range 0..63. In the 4-bit variant of the format, the basic colour intensities are stored in blue-green-red order, while in the 8-bit variant they are stored as red-green-blue.

Specifications

Software

Sample files

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