r
setting register 4.  If value of 0 assigned to register 4 after doing
action 5, subsequent retrieval of picture data gives the "live preview".

<P>
For command 2, the second byte is action code not register number.
The following action codes are known:
<TABLE BORDER=1>
<TR><TH>Code</TH><TH>Argument</TH><TH>Description</TH></TR>
<TR><TD>0</TD><TD>single zero byte</TD><TD>Erase last picure</TD></TR>
<TR><TD>1</TD><TD>single zero byte</TD><TD>Erase all picures (but not animations)</TD></TR>
<TR><T