Logo file
Optional structured files consisting of an index, fix and palette data for CD loading animations.
The BIOS loads these files after checking the IPL file if they are present at the CD's root, at address 0x120000 according to the console's nationality: LOGO_E.PRG, LOGO_U.PRG, or LOGO_J.PRG.
File format
| Address | Size | Description |
| 0 | Word | Data type
(known values: $0000, $0001, $0003) The 8 low bits are stored to 0x11C817 by the bios.
No other bits seem to be checked by the bios. The above is true on the first IPL load only. Some games have different in-game loading graphics that do not follow the above. More information is needed on how these work (SAMSHO4 for example). |
| 0+2 | Longword | Data type
|
| 2+4 | Longword | Absolute data start address (Starting from $120000) |
| ... | ||
| 2+* | Longword | $FFFFFFFF terminator |
Fix tiles data
- Offset (longword) $4000 = tile $200
- Size (longword) $4000 = $200 tiles
- Tile data...
Like the regular fix graphics format, but byteswapped.
Palette data
- Palette number (word), the loading bar seems to use palette 0, so don't use it. Remember that fix tiles can only use the 16 first palettes.
- 16 words of color data.
Map data
- Fix address where to start mapping ($7102 is good)
- Width in tiles (word) $18
- Height in tiles (word) $0B
- Tile numbers/palettes...
Mapped left to right, top to down.
Animation map data
- Fix address where to start mapping ($7102 is good)
- Width in tiles (word)
- Height in tiles (word)
- Number of frames in animation
- Animation speed (in frames)
- Tile numbers/palettes...
Using LOGO files for in-game loading
By default the bios will always use the initial LOGO file during in game loading sequences. It is possible to change this by loading a new data over the logo information at 0x120000. How this gets loaded is not yet confirmed but its suspected that games request the data to be loaded as it would any other data given there is not need for 'LOGO' to be in the file name in this situation. It may also be possible the bios looks out for data being loaded into this region before drawing.
The ability to change the default progress bar (handled by the bios) is also available. The bios places the start address of its code to handle progress bar drawing at 0x11C80C. This code is then always called via 'MOVEA.L 0x11C80C,A0', 'JSR(A0)'. To use a custom progress bar simply place the start address of your custom progress bar code at 0x11C80C. current progress bar state is held at address 0x10F691. Your code should handle all elements of drawing the progress bar.
It appears games plant their custom progress bar code into the default LOGO file as well as any further files that get loaded to this range. Below is the routine used by Samurai Shodown IV.