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  <title>TI-83 Link Protocol Guide - Screenshots</title>
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<p><b>TI-83 Link Protocol Guide</b> - Screenshots</p>
<center>
<h2>
<hr align="center">Screenshots</h2>
</center>
<p>The TI-83's screenshot ability is "silent," which means that the
calculator does not need to be put
in a special mode. Screenshots can be taken any time the calculator is
ready to accept a keypress.</p>
<p>The protocol used for getting a screenshot is shown below. For
information on packet formats, <a href="packet.html">click
here</a>.</p>
<p>
<table bgcolor="#ffffff" border="1" cellspacing="0" width="92%">
  <tbody>
    <tr>
      <th bgcolor="#008800" width="7%"><font color="#ffffff">Step</font></th>
      <th colspan="3" bgcolor="#008800"><font color="#ffffff">Direction</font></th>
      <th bgcolor="#008800" width="80%"><font color="#ffffff">Packet</font></th>
    </tr>
    <tr>
      <td bgcolor="#ffffff" width="7%">
      <p align="center">1 </p>
      </td>
      <td rowspan="4">
      <p align="center"><img src="graphics/comp.gif" alt="Computer"
 align="bottom" border="0" height="33" width="30"> </p>
      </td>
      <td bgcolor="#ffffff">
      <p align="center"><img src="graphics/right.gif" alt="===&gt;"
 align="bottom" border="0" height="13" width="22"> </p>
      </td>
      <td rowspan="4" bgcolor="#ffffff">
      <p align="center"><img src="graphics/calc.gif" alt="Calculator"
 align="bottom" border="0" height="67" width="30"> </p>
      </td>
      <td bgcolor="#ffffff" width="80%">SCR</td>
    </tr>
    <tr>
      <td bgcolor="#ffffff" width="7%">
      <p align="center">2 </p>
      </td>
      <td bgcolor="#ffffff">
      <p align="center"><img src="graphics/left.gif" alt="&lt;==="
 align="bottom" border="0" height="13" width="22"> </p>
      </td>
      <td bgcolor="#ffffff" width="80%">ACK</td>
    </tr>
    <tr>
      <td bgcolor="#ffffff" width="7%">
      <p align="center">3 </p>
      </td>
      <td bgcolor="#ffffff">
      <p align="center"><img src="graphics/left.gif" alt="&lt;==="
 align="bottom" border="0" height="13" width="22"> </p>
      </td>
      <td bgcolor="#ffffff" width="80%">DATA - Format described below.</td>
    </tr>
    <tr>
      <td bgcolor="#ffffff" width="7%">
      <p align="center">4 </p>
      </td>
      <td bgcolor="#ffffff">
      <p align="center"><img src="graphics/right.gif" alt="===&gt;"
 align="bottom" border="0" height="13" width="22"> </p>
      </td>
      <td bgcolor="#ffffff" width="80%">ACK</td>
    </tr>
  </tbody>
</table>
</p>
<p>The data packet contains a 768-byte monochrome bitmap (1 bit per
pixel). Each bit has a value of 1 if the corresponding
pixel is dark or a value of 0 if the corresponding pixel is light.</p>
<p>The pixel order is left-to-right, then top-to-bottom (See figure
below).<br>
Byte 0 defines the first 8 pixels in the left side of the top row of
the screen. Bytes 1-11 define the rest of
the first row, bytes 12-23 define the second row, etc.</p>
<p><u>Example:</u><br>
<table border="0" cellspacing="0" width="100%">
  <tbody>
    <tr>
      <td bgcolor="#ccffcc">PC:</td>
      <td bgcolor="#ccffcc" width="50%"><b><tt>03&nbsp;6D&nbsp;00&nbsp;00</tt></b></td>
      <td bgcolor="#ccffcc" width="50%"><i>Screenshot request</i></td>
    </tr>
    <tr>
      <td bgcolor="#ffcccc">TI:</td>
      <td bgcolor="#ffcccc" width="50%"><b><tt>83&nbsp;56&nbsp;00&nbsp;00</tt></b></td>
      <td bgcolor="#ffcccc" width="50%"><i>Acknowledgement of request</i></td>
    </tr>
    <tr>
      <td bgcolor="#ffcccc">&nbsp;</td>
      <td bgcolor="#ffcccc" width="50%"><b><tt>83&nbsp;15&nbsp;00&nbsp;03&nbsp;</tt></b>&lt;768&nbsp;bytes&nbsp;plus&nbsp;2&nbsp;byte&nbsp;checksum&gt;</td>
      <td bgcolor="#ffcccc" width="50%"><i>Screen data</i></td>
    </tr>
    <tr>
      <td bgcolor="#ccffcc">PC:</td>
      <td bgcolor="#ccffcc" width="50%"><b><tt>03&nbsp;56&nbsp;00&nbsp;00</tt></b></td>
      <td bgcolor="#ccffcc" width="50%"><i>Acknowledgement of data</i></td>
    </tr>
  </tbody>
</table>
</p>
<p>The following figure demonstrates byte ordering of the pixels if the
bitmap is in a 768-element array data[]:</p>
<p><img src="graphics/scrnshot.gif" alt="[pixel grid diagram]"
 align="bottom" border="0" height="274" width="336"></p>
<p>Note that this format is different from the standard Windows bitmap
format, which specifies a value of 1 if
the pixel is light and bottom-to-top row order.</p>
<p>
<table border="0" cellspacing="0" width="100%">
  <tbody>
    <tr>
      <td width="32%">
      <p align="center"><a href="packet.html"><img
 src="graphics/prevpage.gif" alt="[previous page]" align="bottom"
 border="2" height="32" width="32"><br>
Packet Formats</a> </p>
      </td>
      <td width="34%">
      <p align="center"><a href="index.html"><img
 src="graphics/home.gif" alt="[home]" align="bottom" border="2"
 height="32" width="32"><br>
Table of Contents</a> </p>
      </td>
      <td width="34%">
      <p align="center"><a href="manual.html"><img
 src="graphics/nextpage.gif" alt="[next page]" align="bottom" border="2"
 height="32" width="32"><br>
Manual Transfers</a> </p>
      </td>
    </tr>
  </tbody>
</table>
</p>
<hr align="center"><i>Site maintained by Romain Li&eacute;vin (</i><a
 href="mailto:roms@lpg.ticalc.org"><i>roms@lpg.ticalc.org</i></a><i>)
and Tim Singer (</i><a href="mailto:tsinger@gladstone.uoregon.edu"><i>tsinger@gladstone.uoregon.edu</i></a><i>)</i>
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