219 lines
8.8 KiB
HTML
219 lines
8.8 KiB
HTML
<html>
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<head>
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<meta http-equiv="Content-Type"
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content="text/html; charset=iso-8859-1">
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<meta name="GENERATOR" content="Microsoft FrontPage Express 2.0">
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<title>VISION Documentation (LDV): Essential notions</title>
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</head>
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<body background="images/conc2.gif" bgcolor="#FFFFFF">
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<div align="center"><center>
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<table border="0" cellpadding="0" cellspacing="0" width="100%">
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<tr>
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<td align="center" width="17%"><a href="intro.htm"><img
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src="images/cprev.jpg" alt="Previous Chapter "
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border="0" hspace="2" width="46" height="26"></a><a
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href="index.htm"><img src="images/csom.jpg"
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alt="Back to content " border="0" hspace="2" width="26"
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height="26"></a><a href="descrip.htm"><img
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src="images/csuiv.jpg" alt="Next Chapter " border="0"
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hspace="2" width="43" height="26"></a></td>
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<td align="center" valign="top" rowspan="2" width="8%"><p
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align="center"><img src="images/icoprinc.gif" width="59"
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height="71"></p>
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</td>
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<td width="33%"><p align="center"><font color="#0000FF"
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size="5"><strong><em>VISION </em>Documentation
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<em>(LDV)</strong></em></font></p>
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</td>
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<td align="center" valign="top" rowspan="2" width="8%"><p
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align="center"><img src="images/icointro.gif" width="59"
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height="71"></p>
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</td>
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<td valign="top" width="17%"><p align="left">Last update:
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<!--webbot bot="Timestamp" startspan
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s-type="EDITED" s-format="%d/%m/%y" -->01/10/00<!--webbot
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bot="Timestamp" i-checksum="12214" endspan --></p>
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</td>
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</tr>
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<tr>
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<td width="17%"><p align="center"><a
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href="..\..\download/dvldv.zip">Download documentation</a></p>
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</td>
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<td width="33%"><p align="center"><font size="4"><strong>2.
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ESSENTIAL NOTIONS</strong></font></p>
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</td>
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<td align="center" width="17%"> <!--webbot
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bot="HTMLMarkup" startspan --><A HREF="http://www.estat.com/getstats?serial=1390118421">
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<IMG SRC="http://perso.estat.com/cgi-bin/perso/1390118421?page=DocVisionLDV"
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BORDER=0></A>
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<!--webbot
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bot="HTMLMarkup" endspan --></td>
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</tr>
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</table>
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</center></div>
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<hr>
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<p><a name="formats d'images"></a><font size="4"><strong>2.1 Images
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formats</strong></font></p>
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<p>I cannot explain here the bit to bit encoding of an image. Roughly, for
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a number of plans up to 8, a pixel is associated to a colour index in a
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palette. Thus, this index points to the true colour of the pixel. Starting
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with 15 plans, we are in True Color, i.e., each pixel is associated with
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its colour value (thus with 15, 16, 24 or 32 bits). While in True Color,
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it's fairly easy, in palette mode (bit-plane) it becomes quickly complex,
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because each pixel has one of its bits coded in a 16 bits word. This bit
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should be searched, the different bits from one pixel should be put
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together, etc... This becomes quickly tiring and, to be fast, this
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requires assembly optimisation. Thankfully, <em><strong>VISION</strong></em>
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proposes functions to simplify your work with
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<a href="vapi/index.htm#Pr<50>sentation">VAPI</a>.</p>
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<p><em><strong>VISION</strong></em>'s LDVs can work in any of the 3
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following formats (note that there is no interesst for your LDV to handle
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the 3 formats, <em><strong>VISION</strong></em> will transmit the required
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format):</p>
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<ul>
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<li>Standard format</li>
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<li>ATARI format</li>
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<li>Specific format</li>
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</ul>
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<p>This little table specifies these different formats ((R = Red, G =
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Green, B = Blue):</p>
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<div align="center"><center>
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<table border="2" width="100%">
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<tr>
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<td align="center" width="15%"><strong>Format</strong></td>
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<td align="center" width="10%"><strong>Number of bits /
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pixel</strong></td>
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<td align="center" width="75%"><strong>Description</strong></td>
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</tr>
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<tr>
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<td align="center" width="15%">Standard</td>
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<td align="center" width="10%">1, 2, 4, 8</td>
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<td width="75%">Standard format defined by ATARI. The pixel planes
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(16 pixels) are following each other. In True-Color, this format
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maybe exists, but I prefer not to know!</td>
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</tr>
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<tr>
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<td align="center" width="15%">ATARI</td>
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<td align="center" width="10%">1, 2, 4, 8</td>
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<td width="75%">ATARI bit-plane format. Very classical,
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this is the format of ST-Low, ST-Medium and ST-High, then, by
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extension, the format of Falcon's bit-plane modes. Contrary to
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Standard mode, planes are interlaced ((Plan0 - Plan1 - Plan2 -
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Plan 3, for instance for 16 colours))</td>
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</tr>
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<tr>
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<td align="center" width="15%"> </td>
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<td align="center" width="10%">16</td>
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<td width="75%">FALCON True Color mode. Each pixel
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is coded in a 16 bits word such as the following:<br>
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RRRRRVVVVV0BBBBB<br>
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15 --> 0 Bit #<br>
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In fact, the actual encoding is on 15 or 1 pixels. The level of
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green can be coded on 6 bits (65K) instead of 5 (32K).</td>
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</tr>
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<tr>
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<td align="center" width="15%"> </td>
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<td align="center" width="10%">24</td>
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<td width="75%">Sadly <em><strong>VISION</strong></em>
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does not handle this format!</td>
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</tr>
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<tr>
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<td align="center" width="15%"> </td>
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<td align="center" width="10%">32</td>
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<td width="75%">RGB0, R, G, B = red, green or
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blue component on 8 bits (0...255)</td>
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</tr>
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<tr>
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<td align="center" width="15%">Specific</td>
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<td align="center" width="10%">1, 2, 4, 8, 16, 24, 32</td>
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<td width="75%">Specific to the graphic card. No
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hypothesis on the bit encoding for a pixel can be made.</td>
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</tr>
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</table>
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</center></div>
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<p>As far as possible, use the specific format, because it uses the less
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memory. If your LDV has only to handle lines and columns, you don't have
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to pay attention to internal pixel coding, the vro_... VDI functions will
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handle it.</p>
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<p>If you have to handle pixels, I recommand to use the ATARI format,
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because <em><strong>VISION</strong></em> allows to get very easily the
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indexes through its <a
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href="vapi/index.htm#Pr<50>sentation">VAPI</a>.</p>
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<p>The standard format is not very useful, except internally in
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<em><strong>VISION</strong></em> to display the images correctly. except
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if you have developed equivalent functions to those proposed in
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<a href="vapi/index.htm#Pr<50>sentation">VAPI</a>, I would advise not to use
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this format.</p>
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<p> </p>
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<p><a name="prog"></a><font size="4"><strong>2.2 Programing</strong></font></p>
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<p>You have to know how to program in C! Normally, LDVs do not depend on
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the compiler (I did my best but, as I use only Pure C, I cannot be really
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sure).</p>
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<p>You have to be fluent in C and not be afraid of handling pointers on
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structures and functions.</p>
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<p>If you know LDGs, this will be useful but it is not mandatory, the LDV
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skeleton hides them fairly well.</p>
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<hr>
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<div align="center"><center>
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<table border="0" cellpadding="0" cellspacing="0" width="100%">
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<tr>
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<td align="center" width="17%"><a href="intro.htm"><img
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src="images/cprev.jpg" alt="Previous chapter "
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border="0" hspace="2" width="46" height="26"></a><a
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href="index.htm"><img src="images/csom.jpg"
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alt="Back to content " border="0" hspace="2" width="26"
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height="26"></a><a href="descrip.htm"><img
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src="images/csuiv.jpg" alt="Next Chapter " border="0"
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hspace="2" width="43" height="26"></a></td>
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<td align="center" valign="top" rowspan="2" width="8%"><p
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align="center"><img src="images/icoprinc.gif" width="59"
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height="71"></p>
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</td>
|
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<td width="33%"><p align="center"><font color="#0000FF"
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size="5"><strong><em>VISION </em>Documentation
|
||
<em>(LDV)</strong></em></font></p>
|
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</td>
|
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<td align="center" valign="top" rowspan="2" width="8%"><p
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align="center"><img src="images/icointro.gif" width="59"
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height="71"></p>
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</td>
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<td valign="top" width="17%"><p align="left">Last update:
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<!--webbot bot="Timestamp" startspan
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s-type="EDITED" s-format="%d/%m/%y" -->01/10/00<!--webbot
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||
bot="Timestamp" i-checksum="12214" endspan --></p>
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||
</td>
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</tr>
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<tr>
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<td width="17%"><p align="center"><a
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href="..\..\download/dvldv.zip">Download documentation</a></p>
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||
</td>
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||
<td width="33%"><p align="center"><font size="4"><strong>2.
|
||
ESSENTIAL NOTIONS</strong></font></p>
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||
</td>
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||
<td valign="top" width="17%"> </td>
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||
</tr>
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</table>
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</center></div>
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</body>
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</html>
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