ther games do is constantly
vary the left and right values using HDMA.

<P><A NAME="Reg2123"></A><B><FONT FACE="Lucida Console">Register $2123/$2124:
Window mask settings (2*1b/W)</FONT></B>

<P><TT>High Byte Low Byte&nbsp; 4: Settings for BG4&nbsp; 3: Settings for
BG3</TT>
<BR><TT>44443333&nbsp; 22221111&nbsp; 2: Settings for BG2&nbsp; 1: Settings
for BG1</TT>

<P><TT>Each BG has four bits, which have the following meanings:</TT>
<BR><TT>dcba&nbsp;&nbsp;&nbsp; d: Enable Window 2&nbsp; c: Clip Window
2 in o