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https://github.com/pfusik/xasm.git
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74 lines
2.0 KiB
HTML
74 lines
2.0 KiB
HTML
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<HTML>
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<HEAD>
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<TITLE>PIA Documentation</TITLE>
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</HEAD>
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<BODY BACKGROUND="atari.gif">
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<CENTER>
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<H1>PIA Documentation</H1>
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by <A HREF="mailto:pfusik@elka.pw.edu.pl">Fox/Taquart</A><P>
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<HR>
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<P>
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<H2>Registers</H2>
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<TABLE BORDER>
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<TR><TD><I> Address </I></TD><TD><I> Read/Write register </I></TD></TR>
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<TR><TD ALIGN=center><TT>^30</TT></TD><TD><A HREF="#porta">PORTA</A></TD></TR>
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<TR><TD ALIGN=center><TT>^31</TT></TD><TD><A HREF="#portb">PORTB</A></TD></TR>
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<TR><TD ALIGN=center><TT>^32</TT></TD><TD><A HREF="#pactl">PACTL</A></TD></TR>
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<TR><TD ALIGN=center><TT>^33</TT></TD><TD><A HREF="#pbctl">PBCTL</A></TD></TR>
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</TABLE>
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<P>
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<HR>
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<P>
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<H2>Description</H2>
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</CENTER>
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<A NAME="porta"><U>PORTA</U>
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- <B>Port A</B><BR>
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A bit is RESET on an event<BR>
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bit 0 - joystick 0 up<BR>
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bit 1 - joystick 0 down<BR>
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bit 2 - joystick 0 left / paddle 0 button<BR>
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bit 3 - joystick 0 right / paddle 1 button<BR>
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bit 4 - joystick 1 up<BR>
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bit 5 - joystick 1 down<BR>
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bit 6 - joystick 1 left / paddle 0 button<BR>
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bit 7 - joystick 1 right / paddle 1 button<P>
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<A NAME="portb"><U>PORTA</U>
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- <B>Port B</B><BR>
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Controls memory.<BR>
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bit 0 - $c000-$cfff and $d800-$ffff:<BR>
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0 - RAM<BR>
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1 - OS ROM<BR>
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bit 1 - $a000-$bfff:<BR>
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0 - BASIC ROM<BR>
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1 - RAM<BR>
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bits 6-2 - extended memory control<BR>
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bit 7 - $5800-$5fff:<BR>
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0 - SELF TEST ROM<BR>
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1 - RAM<P>
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<A NAME="pactl"><U>PACTL</U>
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- <B>Port A Control</B><BR>
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bits 1-0 - interrupts control (?) = 00<BR>
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bit 2 - PORTA control<BR>
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0 - input/output configuration<BR>
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1 - data register<BR>
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bit 3 - cassette motor<BR>
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0 - on<BR>
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1 - off<BR>
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bits 7-4 - interrupts status (?) = 0011<P>
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<A NAME="pbctl"><U>PBCTL</U>
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- <B>Port B Control</B><BR>
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bits 1-0 - interrupts control (?) = 00<BR>
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bit 2 - PORTB control<BR>
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0 - input/output configuration<BR>
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1 - data register<BR>
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bit 3 - serial devices command line<BR>
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0 - on<BR>
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1 - off<BR>
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bits 7-4 - interrupts status (?) = 0011<P>
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</BODY>
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</HTML>
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