Master System

Revision for “Master System” created on September 6, 2017 @ 13:46:56

Title
Master System
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The Sega Master System, released in 1986, is a third-generation home video game console manufactured by Sega. [toc] <h1>Technical Specifications</h1> <h1>Region Detect</h1> The region detection code used in Master Games attempts to write to the two most significant bits in I/O port $3F and to read back the value at I/O port $DD. Japanese systems will not readback the write value at $DD, overseas systems will. <pre><span class="co1">;==============================================================</span> <span class="co1">; Region detector</span> <span class="co1">; Returns a=1 for Japanese, 0 for export</span> <span class="co1">; Based on code found in many Sega games (eg. Super Tennis)</span> <span class="co1">;==============================================================</span> <span class="re2">IsJapanese:</span>     <span class="kw1">ld</span> <span class="kw2">a</span>,<span class="re1">%11110101</span>  <span class="co1">; Output 1s on both TH lines</span>     <span class="kw1">out</span> <span class="br0">(</span><span class="re0">$3f</span><span class="br0">)</span>,<span class="kw2">a</span>     <span class="kw1">in</span> <span class="kw2">a</span>,<span class="br0">(</span><span class="re0">$dd</span><span class="br0">)</span>     <span class="kw1">and</span> <span class="re1">%11000000</span>  <span class="co1">; See what the TH inputs are</span>     <span class="kw1">cp</span> <span class="re1">%11000000</span>  <span class="co1">; If the input does not match the output then it's a Japanese system</span>     <span class="kw1">jp</span> nz,_IsJap     <span class="kw1">ld</span> <span class="kw2">a</span>,<span class="re1">%01010101</span>  <span class="co1">; Output 0s on both TH lines</span>     <span class="kw1">out</span> <span class="br0">(</span><span class="re0">$3f</span><span class="br0">)</span>,<span class="kw2">a</span>     <span class="kw1">in</span> <span class="kw2">a</span>,<span class="br0">(</span><span class="re0">$dd</span><span class="br0">)</span>     <span class="kw1">and</span> <span class="re1">%11000000</span>  <span class="co1">; See what the TH inputs are</span>     <span class="kw1">jp</span> nz,_IsJap    <span class="co1">; If the input does not match the output then it's a Japanese system</span>     <span class="kw1">ld</span> <span class="kw2">a</span>,<span class="re1">%11111111</span>  <span class="co1">; Set everything back to being inputs</span>     <span class="kw1">out</span> <span class="br0">(</span><span class="re0">$3f</span><span class="br0">)</span>,<span class="kw2">a</span>     <span class="kw1">ld</span> <span class="kw2">a</span>,<span class="nu0">0</span>     <span class="kw1">ret</span> <span class="re2">_IsJap:</span>     <span class="kw1">ld</span> <span class="kw2">a</span>,<span class="nu0">1</span>     <span class="kw1">ret</span></pre> <h1>Accessories</h1> <ul> <li><a href="http://db-electronics.ca/wiki/wikis/consoles/master-system/3d-glasses-adapter/">3D Glasses Adapter</a></li> </ul> <h1>Schematics</h1> <ul> <li>[google-drive-embed url="https://drive.google.com/file/d/0BxWY40xxhh0vNmxENUY4SVVNTVE/view?usp=drivesdk" title="sms1_schematic-1.gif" icon="https://ssl.gstatic.com/docs/doclist/images/icon_11_image_list.png" newwindow="yes" plain="yes" style="normal"]</li> <li>[google-drive-embed url="https://drive.google.com/file/d/0BxWY40xxhh0vVk5QekJIQTFkRXM/view?usp=drivesdk" title="SMS2_Schematic_Sheet1.png" icon="https://ssl.gstatic.com/docs/doclist/images/icon_11_image_list.png" newwindow="yes" plain="yes" style="normal"]</li> <li>[google-drive-embed url="https://drive.google.com/file/d/0BxWY40xxhh0vRXd3SHFSMDNhVVE/view?usp=drivesdk" title="SMS2_Schematic_Sheet2.png" icon="https://ssl.gstatic.com/docs/doclist/images/icon_11_image_list.png" newwindow="yes" plain="yes" style="normal"]</li> <li>[google-drive-embed url="https://drive.google.com/file/d/0BxWY40xxhh0vTVZXWjhvZHd6Umc/view?usp=drivesdk" title="SMS2_Schematic_Sheet3.png" icon="https://ssl.gstatic.com/docs/doclist/images/icon_11_image_list.png" newwindow="yes" plain="yes" style="normal"]</li> </ul> &nbsp;
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René

Electronics engineer and retrogaming fanatic!