Well, actually it's fractional values. I find the following table handy when attempting to convert programs written for those sorts of monitors.
Colour # | R | G | B |
---|---|---|---|
0 | 0 | 0 | 0 |
1 | 0 | 0 | 2/3 |
2 | 0 | 2/3 | 0 |
3 | 0 | 2/3 | 2/3 |
4 | 2/3 | 0 | 0 |
5 | 2/3 | 0 | 2/3 |
6 | 2/3 | 1/3 | 0 |
7 | 2/3 | 2/3 | 2/3 |
8 | 1/3 | 1/3 | 1/3 |
9 | 1/3 | 1/3 | 1 |
10 | 1/3 | 1 | 1/3 |
11 | 1/3 | 1 | 1 |
12 | 1 | 1/3 | 1/3 |
13 | 1 | 1/3 | 1 |
14 | 1 | 1 | 1/3 |
15 | 1 | 1 | 1 |
I don't need to know the remaining 48 (EGA-only) colours too often so I haven't got around to them yet.