OS/2 Boot Logo
(Category:Booting) |
|||
| Line 20: | Line 20: | ||
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. | 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. | ||
| − | GBM says that it uses EXEPACK compression, but this is unconfirmed | + | GBM says that it uses [[EXEPACK]] compression, but this is unconfirmed. |
This much is known about an element: | This much is known about an element: | ||
Revision as of 18:06, 4 April 2022
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.
No public format specifications are known.
Format details
This is an incomplete, and possibly inaccurate, description of the format.
The image data is separated into four bit-planes, which are compressed and stored separately.
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.
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.
GBM says that it uses EXEPACK compression, but this is unconfirmed.
This much is known about an element:
| Opcode (N) | Following bytes | Description |
|---|---|---|
| 0 | 0 | End-of-data marker |
| 0 | count, val | RLE: Emit count bytes of value val. |
| N mod 4 = 0 | ... | Uncompressed: Emit the next N/4 bytes literally. |
| other | ... | Unknown; apparently one or more other (LZ?) compression methods |
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)
Sample files
- PrepLogo → logos.zip
- WARPLOGO.ZIP - Older version of the above?
- http://www.altsan.org/os2/graphics/index.html
- os2logo
