The idea that such multi-color trickery was possible came to me some time ago, as I was looking at reenigne’s code for patching up composite CGA emulation in DOSBox; messing with that patch during development gave me a much better picture of composite CGA’s inner workings. When I had ironed out the basic concept for this hack, I divulged it to reenigne for ‘peer review’ and for testing on real hardware. Soon enough, we had an improved recipe:
Take two familiar (though officially undocumented) tweaks. Blend to an even mixture producing a new effect.
Add one crucial new trick – an ingredient of reenigne’s devising.
Test and calibrate until blue in the face.