I was watching 8-bit guy's Compaq portable restoration, and he pointed out the special adapter on the Compaq's CGA card that allowed both CGA and mono modes on the internal (composite?) display.

As they are special video cards, I got to wondering how one would replace one with another CGA cad with the same capabilities, should the original fail?

I've also read somewhere about putting out to composite with the Raspberry Pi. Which made me wonder if A) it could output to the Compaq's internal monitor, and B) if it could emulate a CGA composite mode. Why? I dunno. That's just where my mind went.

Here's part 1 of 8-Bit Guy's video on repairing the Compaq Portable. There is a part 2, wherein he focuses on repairing the keyboard.

Anyway, back to my original question. How would one replace the CGA card and retain compatibility with the internal monitor?