AT&T 6300 Programmer's Manual page 136

Graphics
5-14
The COLOR (Super Resolution) statement
allows you to specify the graphics foreground
color. The COLOR statement also allows you to
specify 'inverse video', when you display
characters.
Displaying Characters
The size of the characters is the same as in
80-column Text Mode.
The character foreground color is 1 (white) and
the character background 0 (black), unless you
specify 'inverse video' by the COLOR
statement.