<HTML> <HEAD> <TITLE>ANTIC Documentation</TITLE> </HEAD> <BODY BACKGROUND="atari.gif"> <CENTER> <H1>ANTIC Documentation</H1> by <A HREF="mailto:pfusik@elka.pw.edu.pl">Fox/Taquart</A><P> <HR> <P> <H2>Registers</H2> <TABLE BORDER> <TR><TD><I> Address </I></TD><TD><I> Read register </I></TD><TD><I> Write register </I></TD></TR> <TR><TD ALIGN=center><TT>^40</TT></TD><TD>unused</TD><TD><A HREF="#dmactl">DMACTL</A></TD></TR> <TR><TD ALIGN=center><TT>^41</TT></TD><TD>unused</TD><TD><A HREF="#chrctl">CHRCTL</A></TD></TR> <TR><TD ALIGN=center><TT>^42</TT></TD><TD>unused</TD><TD><A HREF="#dlptr">DLPTRL</A></TD></TR> <TR><TD ALIGN=center><TT>^43</TT></TD><TD>unused</TD><TD><A HREF="#dlptr">DLPTRH</A></TD></TR> <TR><TD ALIGN=center><TT>^44</TT></TD><TD>unused</TD><TD><A HREF="#hscrol">HSCROL</A></TD></TR> <TR><TD ALIGN=center><TT>^45</TT></TD><TD>unused</TD><TD><A HREF="#vscrol">VSCROL</A></TD></TR> <TR><TD ALIGN=center><TT>^46</TT></TD><TD>unused</TD><TD>unused</TD></TR> <TR><TD ALIGN=center><TT>^47</TT></TD><TD>unused</TD><TD><A HREF="#pmbase">PMBASE</A></TD></TR> <TR><TD ALIGN=center><TT>^48</TT></TD><TD>unused</TD><TD>unused</TD></TR> <TR><TD ALIGN=center><TT>^49</TT></TD><TD>unused</TD><TD><A HREF="#chbase">CHBASE</A></TD></TR> <TR><TD ALIGN=center><TT>^4A</TT></TD><TD>unused</TD><TD><A HREF="#wsync">WSYNC</A></TD></TR> <TR><TD ALIGN=center><TT>^4B</TT></TD><TD><A HREF="#vcount">VCOUNT</A></TD><TD>unused</TD></TR> <TR><TD ALIGN=center><TT>^4C</TT></TD><TD><A HREF="#lpenh">LPENH</A></TD><TD>unused</TD></TR> <TR><TD ALIGN=center><TT>^4D</TT></TD><TD><A HREF="#lpenv">LPENV</A></TD><TD>unused</TD></TR> <TR><TD ALIGN=center><TT>^4E</TT></TD><TD>unused</TD><TD><A HREF="#nmien">NMIEN</A></TD></TR> <TR><TD ALIGN=center><TT>^4F</TT></TD><TD><A HREF="#nmist">NMIST</A></TD><TD>unused</TD></TR> </TABLE> <P> <HR> <P> <H2>Description</H2> </CENTER> <A NAME="chbase"><U>CHBASE</U> - <B>Characters base</B><BR> Contains high byte of character set in text modes.<P> <A NAME="chrctl"><U>CHRCTL</U> - <B>Characters control</B><BR> bit 0 - display characters 128-255 as spaces<BR> bit 1 - display characters 128-255 as inverse<BR> bit 2 - display all characters upside down<P> <A NAME="dlptr"><U>DLPTRL</U> <U>DLPTRH</U> - <B>Display List pointer</B><P> <A NAME="dmactl"><U>DMACTL</U> - <B>DMA control</B><BR> bits 1,0 - width of screen<BR> 00 - screen off<BR> 01 - narrow screen - 256 pixels<BR> 10 - normal screen - 320 pixels<BR> 11 - wide screen - 384 pixels<BR> bits 3,2 - DMA for Players/Missiles<BR> 00 - no DMA for P/MG<BR> 01 - DMA for missiles<BR> 10 - DMA for players and missiles<BR> 11 - DMA for players and missiles<BR> bit 4 - P/MG resolution<BR> 0 - 120 lines<BR> 1 - 240 lines<BR> bit 5 - DMA for Display List<BR> bits 7-6 - unused<P> <A NAME="hscrol"><U>HSCROL</U> - <B>Horizontal scroll</B><P> <A NAME="lpenh"><U>LPENH</U> - <B>Light pen horizontal position</B><P> <A NAME="lpenv"><U>LPENV</U> - <B>Light pen vertical position</B><P> <A NAME="nmien"><U>NMIEN</U> - <B>NMI enable</B><BR> bits 5-0 - unused<BR> bit 6 - enable VBLKI<BR> bit 7 - enable DLI<P> <A NAME="nmist"><U>NMIST</U> - <B>NMI status</B><BR> bits 5-0 - unused<BR> bit 6 - VBLKI occured<BR> bit 7 - DLI occured<P> <A NAME="pmbase"><U>PMBASE</U> - <B>Player/missile base</B><BR> High byte of P/MG data<P> <A NAME="vcount"><U>VCOUNT</U> - <B>Vertical count</B><BR> Contains number of scanline divided by 2.<P> <A NAME="vscrol"><U>VSCROL</U> - <B>Vertial scroll</B><P> <A NAME="wsync"><U>WSYNC</U> - <B>Wait for synchronization</B><BR> Any value written to this register stops CPU until right border of normal screen is reached.<P> </BODY> </HTML>