(SET-BK-COLOR color)

Sets the background color to the specified color. Color can be any of the following (for CGA-likes too):
Symbol Equivalent number
{\itt 'BLACK} 0
{\itt 'BLUE} 1
{\itt 'GREEN} 2
{\itt 'CYAN} 3
{\itt 'RED} 4
{\itt 'MAGENTA} 5
{\itt 'BROWN} 6
{\itt 'LIGHT-GRAY} 7
{\itt 'DARK-GRAY} 8
{\itt 'LIGHT-BLUE} 9
{\itt 'LIGHT-GREEN} 10
{\itt 'LIGHT-CYAN} 11
{\itt 'LIGHT-RED} 12
{\itt 'LIGHT-MAGENTA} 13
{\itt 'YELLOW} 14
{\itt 'WHITE} 15

On CGA-ish and EGA systems, SET-BK-COLOR only changes the entry 0 of the palette.

If you totally re-map the palette with a EGA or VGA adapter, use SET-BK-COLOR with numbers rather than symbols.