bsp; d: BG4 enable&nbsp; c: BG3
enable</TT>
<BR><TT>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
b: BG2 enable&nbsp; a: BG1 enable</TT>

<P>These registers are formatted the same as the visibility designation
<A HREF="#Reg212C">registers $212C and $212D</A>.&nbsp; A bit must be set
in both $212C and $212E or $212D or $212E in order for windows to be enabled
for that layer (BG or sprite