OS/2 Boot Logo

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The file used by the operating system is named "OS2LOGO", with no filename extension. Inactive logo files are conventionally given the extension '''.lgo'''.
 
The file used by the operating system is named "OS2LOGO", with no filename extension. Inactive logo files are conventionally given the extension '''.lgo'''.
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No public format specifications are known.
 
  
 
== Format details ==
 
== Format details ==
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''This is an incomplete, and possibly inaccurate, description of the format.''
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The image data is separated into four bit-planes, each of which is compressed with the [[EXEPACK2]] scheme.
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The image data is separated into four bit-planes, which are compressed and stored separately.
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The file begins with a 32-byte header of 8 four-byte integers: the file offset of plane 0, the length of plane 0, the offset of plane 1, the length of plane 1, and so on.
 
The file begins with a 32-byte header of 8 four-byte integers: the file offset of plane 0, the length of plane 0, the offset of plane 1, the length of plane 1, and so on.
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A compressed plane of data seems to consist of a sequence of elements, each of which begins with an opcode byte, followed by a variable number of data bytes.
 
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GBM says that it uses [[EXEPACK]] compression, but this is unconfirmed.
 
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This much is known about an element:
 
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{| class="wikitable"
 
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! Opcode (N)
 
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! Following bytes
 
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! Description
 
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|-
 
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|0 || 0 || End-of-data marker
 
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|-
 
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|0 || ''count'', ''val'' || RLE: Emit ''count'' bytes of value ''val''.
 
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|-
 
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|N mod 4 = 0  || ... || Uncompressed: Emit the next N/4 bytes literally.
 
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|-
 
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|other || ... || Unknown; apparently one or more other (LZ?) compression methods
 
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|}
 
  
 
This is the VGA palette used by GBM:
 
This is the VGA palette used by GBM:
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* [http://heikon.home.tlink.de/ GBM] → GBMLOGO (write-only; requires MAKELOGO)
 
* [http://heikon.home.tlink.de/ GBM] → GBMLOGO (write-only; requires MAKELOGO)
 
* [http://cd.textfiles.com/hobbesos29804/disk1/GRAPHICS/BMP2LOGO.ZIP BMP2LOGO.ZIP] (OS/2 software; write-only; requires MAKELOGO)
 
* [http://cd.textfiles.com/hobbesos29804/disk1/GRAPHICS/BMP2LOGO.ZIP BMP2LOGO.ZIP] (OS/2 software; write-only; requires MAKELOGO)
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* [https://kannegieser.net/veit/programm/index_e.htm] → lgoproc
  
 
== Sample files ==
 
== Sample files ==

Revision as of 18:41, 26 May 2022

File Format
Name OS/2 Boot Logo
Ontology
Extension(s) (none), .lgo
Released 1994

OS/2 Boot Logo is a compressed raster graphics format used for the logo shown when OS/2 Warp operating systems boot. Images are 640×400 (Warp 3), or 640×480 (Warp 4), with 16 colors.

The file used by the operating system is named "OS2LOGO", with no filename extension. Inactive logo files are conventionally given the extension .lgo.

Format details

The image data is separated into four bit-planes, each of which is compressed with the EXEPACK2 scheme.

The file begins with a 32-byte header of 8 four-byte integers: the file offset of plane 0, the length of plane 0, the offset of plane 1, the length of plane 1, and so on.

This is the VGA palette used by GBM: 

#000000,#000080,#008000,#008080,#800000,#800080,#808000,#808080,
#cccccc,#0000ff,#00ff00,#00ffff,#ff0000,#ff00ff,#ffff00,#ffffff

Software

  • PMView Pro
  • PrepLogo (OS/2 software; write-only)
  • MAKELOGO - A utility on the IBM OS/2 Developer Connection CDs, which can create a logo file from raw bitmap files
  • GBM → GBMLOGO (write-only; requires MAKELOGO)
  • BMP2LOGO.ZIP (OS/2 software; write-only; requires MAKELOGO)
  • [1] → lgoproc

Sample files

Retrieved from "http://fileformats.archiveteam.org/index.php?title=OS/2_Boot_Logo&oldid=42693"
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