IBM RT Series Hardware Reference Manual page 30

When operating in Mode 1, the display maps the 4 input bits into
16 of the possible 64 colors as shown in the following chart.
I
R
G
B Color
Rr
Gg
Bb
0 0 0
0 Black
00 00
00
0 0 0
1 Blue
00 00
1 0
0 0 1
0 Green
00 1 0
00
0 0 1 1
Cvan
00 1 0
1 0
0 1 0
0
Red
1 0 00
00
0
1 0
1
Magenta 1 0 00
1 0
0
1 1
0 Brown
1 0
01
00
0
1 1
1
Grav 1
1 0 1 0 1 0
1 0
0
0 Grav 2
01 01
01
1 0 0
1 Light Blue
01 01
1 1
1 0 1
0 Light Green
01 1 1
01
1 0 1
1 Light Cvan
01 1 1
1 1
1 1 0
0 Light Red
1 1 01
01
1 1 0
1 Light Magenta
1 1 01
1 1
1 1 1
0 Light Yellow
1 1 1 1
01
1 1 1
1 White
1 1 1 1
1 1
Note: The R G and B are the most significant bits. The r g
and b are the least significant bits.
4 IBM Enhanced Color Display