223cc6685e
git-svn-id: svn://svn.compuextreme.de/Viitor/V963/Viitor_cc65@5933 504e572c-2e33-0410-9681-be2bf7408885
131 lines
4.1 KiB
HTML
131 lines
4.1 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
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<HTML>
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<META NAME="GENERATOR" CONTENT="LinuxDoc-Tools 0.9.20">
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<TITLE>Atari specific information for cc65: Loadable drivers</TITLE>
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<LINK HREF="atari-6.html" REL=next>
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<LINK HREF="atari-4.html" REL=previous>
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<LINK HREF="atari.html#toc5" REL=contents>
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<A HREF="atari-6.html">Next</A>
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<A HREF="atari.html#toc5">Contents</A>
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<HR>
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<H2><A NAME="s5">5.</A> <A HREF="atari.html#toc5">Loadable drivers</A></H2>
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<H2><A NAME="ss5.1">5.1</A> <A HREF="atari.html#toc5.1">Graphics drivers</A>
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</H2>
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<P>Currently there are no graphics drivers available for the Atari platform.
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However, the runtime library provides a function named _graphics, with
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a mode parameter just like the BASIC GRAPHICS command. This function will
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switch to the requested graphics mode.
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There are currently no functions available to access the graphics
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memory. The access must be implemented manually.</P>
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<P>Many graphics modes require more memory than the text screen which is
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in effect when the program starts up. Therefore the programmer has to
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tell the program beforehand the memory requirements of the graphics
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modes the program intends to use.
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This can be done by using the __RESERVED_MEMORY__ linker config
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variable. The number specified there describes the number of bytes to
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subtract from the top of available memory as seen from the runtime
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library. This memory is then used by the screen buffer.</P>
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<P>The numbers for the different graphics modes presented below should
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only be seen as a rule of thumb. Since the screen buffer memory needs
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to start at specific boundaries, the numbers depend on the current top
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of available memory.
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The following numbers were determined by a BASIC program.</P>
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<P>
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<BR><CENTER>
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<TABLE BORDER><TR><TD>
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graphics mode</TD><TD>reserved memory</TD></TR><TR><TD>
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0</TD><TD>1</TD></TR><TR><TD>
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1</TD><TD>1</TD></TR><TR><TD>
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2</TD><TD>1</TD></TR><TR><TD>
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3</TD><TD>1</TD></TR><TR><TD>
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4</TD><TD>1</TD></TR><TR><TD>
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5</TD><TD>182</TD></TR><TR><TD>
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6</TD><TD>1182</TD></TR><TR><TD>
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7</TD><TD>3198</TD></TR><TR><TD>
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8</TD><TD>7120</TD></TR><TR><TD>
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9</TD><TD>7146</TD></TR><TR><TD>
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10</TD><TD>7146</TD></TR><TR><TD>
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11</TD><TD>7146</TD></TR><TR><TD>
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12</TD><TD>162</TD></TR><TR><TD>
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13</TD><TD>1</TD></TR><TR><TD>
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14</TD><TD>3278</TD></TR><TR><TD>
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15</TD><TD>7120</TD></TR><TR><TD>
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16</TD><TD>1</TD></TR><TR><TD>
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17</TD><TD>1</TD></TR><TR><TD>
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18</TD><TD>1</TD></TR><TR><TD>
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19</TD><TD>1</TD></TR><TR><TD>
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20</TD><TD>1</TD></TR><TR><TD>
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21</TD><TD>184</TD></TR><TR><TD>
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22</TD><TD>1192</TD></TR><TR><TD>
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23</TD><TD>3208</TD></TR><TR><TD>
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24</TD><TD>7146</TD></TR><TR><TD>
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25</TD><TD>7146</TD></TR><TR><TD>
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26</TD><TD>7146</TD></TR><TR><TD>
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27</TD><TD>7146</TD></TR><TR><TD>
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28</TD><TD>160</TD></TR><TR><TD>
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29</TD><TD>1</TD></TR><TR><TD>
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30</TD><TD>3304</TD></TR><TR><TD>
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31</TD><TD>7146
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</TD></TR></TABLE>
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<CAPTION>reserved memory required for different graphics modes</CAPTION>
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</CENTER><BR>
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</P>
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<P>The values of "1" are needed because the graphics command crashes if
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it doesn't have at least one byte available. This seems to be a bug of
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the Atari ROM code.</P>
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<H2><A NAME="ss5.2">5.2</A> <A HREF="atari.html#toc5.2">Extended memory drivers</A>
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</H2>
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<P>Currently there are no extended memory drivers available for the Atari
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platform.</P>
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<H2><A NAME="ss5.3">5.3</A> <A HREF="atari.html#toc5.3">Joystick drivers</A>
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</H2>
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<P>
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<DL>
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<DT><B><CODE>atari-stdjoy.joy</CODE></B><DD><P>Supports up to four standard joysticks connected to the joystick ports of
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the Atari.</P>
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</DL>
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</P>
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<H2><A NAME="ss5.4">5.4</A> <A HREF="atari.html#toc5.4">Mouse drivers</A>
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</H2>
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<P>Currently no drivers available (in fact, the API for loadable mouse drivers
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does not exist). There is a static driver you can use.</P>
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<H2><A NAME="ss5.5">5.5</A> <A HREF="atari.html#toc5.5">RS232 device drivers</A>
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</H2>
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<P>Currently there are no RS232 loadable drivers available for the Atari
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platform. There is a static driver you can use.</P>
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<HR>
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