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0e1f616
(Get the code!)
Be aware, when testing this, that other problems can also cause this symptom.
If you are using a Radeon X1600 video card, these patches may not work for you. When using this card (at least the one that I borrowed) the Color Plane Enable register is apparently ignored. Not only does changing the register from 0xF to 0x7 fail to mask bright colors, changing it to zero, in an attempt to disable all color planes, still allows all sixteen colors to be displayed.
This is true whether or not usplash is run.
Thinking that there might be a control bit in some extended register that causes the Color Plane Enable register to be bypassed, and that some other boot-time software was modifying it and not restoring it, I looked through the somewhat limited documentation available for this card, searching for such a bit. But I came up empty handed.
By then I was beginning to think that this might simply be a VGA compatibility issue. ("VGA Compatible" is a term sometimes used loosely by manufacturers.) So I wrote a snippet of code to a boot floppy, to be executed immediately at boot-time. This code wrote 0x7 to the Color Plane Enable register and succeeded in masking the bright colors on all the machines I booted with it, except for the one with the Radeon X1600.
So it looks like there may be a hardware problem with the X1600. I can't really say for sure. I suppose it is possible that the PC's BIOS is messing with the registers on the Radeon before passing control to the boot floppy, but it seems unlikely. Or the X1600 I used could be defective.
I would be interested to hear from any other X1600 or other Radeon users who are experiencing similar problems, or not. A quick test to run is this:
setfont Lat15-Fixed16 ; setfont Uni1-Fixed16 ; showconsolefont
This should show all 512 glyphs of the Uni1-Fixed16 font, all of the same color and intensity. (This works even if you booted with usplash.) If this is what you see, your video card is working properly (or at least its Color Plane Enable logic is). If the glyphs on the right are a different color or intensity than those on the left, you may possibly have the same problem I found when using the Radeon X1600.
I could supply the test boot floppy image if the above test fails for anyone, and further testing is desired.