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+<title>OS/2 subsystem for ReactOS</title>
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+<h1><b>OS/2 subsystem for ReactOS (ROS/2)</b></h1>
+<h2><font color="#009966">Introduction</font></h2>
+<p>The OS/2 subsystem is being developed to enable NT-like systems (like WinNT
+ and ReactOS) to run 32-Bit OS/2 applications natively. With this it shall provide
+ binary compatiblility on x86-Based systems. It is intended to port the ROS/2
+ also to other platforms supported by ReactOS / NT. It is planned to provide
+ source code compatibility on these platforms. Yeeahh, OS/2 for PowerPC is in
+ sight.</p>
+<h2><font color="#009966">Components</font></h2>
+<p>ROS/2 consists of the following components:</p>
+<ul>
+ <li>OS2SS.EXE - A native application that implements the personality of the
+ OS/2 kernel.</li>
+ <li>OS2.EXE - A win32 application that does the interaction of the OS/2 apps
+ with the desktop.</li>
+ <li>Core DLLs - These DLLs that make OS/2 programs interface with the kernel/sub
+ system (i.E. DOSCALLS.DLL). </li>
+ <li>Additional DLLs - DLLs that provide additional APIs for OS/2 apps. This
+ includes Presentation Manager.</li>
+</ul>
+<h2><font color="#009966">Current state</font></h2>
+<p>Up to now just a fragment of DOSCALLS.DLL exists. The biggest problem are the
+ os2 API headers which are (C) by IBM. So help is still welcome.</p>
+<h2><font color="#009966">16-Bit issues</font></h2>
+<p>It is not intended to support 16-bit OS/2 applications. This would make the
+ system inconsistent and produce much more work that use. But there is still
+ one issue: Current textmode applications are either 16-bit or use thunking to
+ call the 16-bit APIs. These 32-Bit thunking applications have to be supported.
+ We are still thinking how to accomplish that. </p>
+<h2><font color="#009966">32-Bit issues</font></h2>
+<p>It is planned to replace the current MOU- KBD- MSG- and VIO- subsystems with
+ the <a href="http://homepages.tesco.net/%7EJ.deBoynePollard/Softwares/conapi.html">Unicode
+ Console API</a>. This is also the foundation for other platforms we want to
+ provide source code compatibility with. So nearly every 32-Bit processor can
+ be supported. It sould even be possible to implement a 64-bit OS/2 API.</p>
+<h2><font color="#009966">Architecture</font></h2>
+<p>To understand the architecture of ReactOS or WinNT read a book from the "Inside
+ Windows NT"-series. The architecture of ROS/2 is like every normal subsystem.
+ When OS2SS.EXE starts, it creates an object directory named os2 and therein
+ it creates a port object with the name Os2API. A port is something like a socket.
+ Two programs can comunicate with each other via a port. The port Os2API provides
+ the LPC API of the OS2SS.EXE - the actual subsystem. <br>
+ Every OS/2 program that is loaded, is linked with DOSCALLS.DLL and NTDLL.DLL
+ - the interface to the NT-kernel. Since DOSCALLS is implemented using NTDLL.DLL,
+ every OS/2 app has it in its adress space. Many functions in DOSCALLS.DLL are
+ implemented by just wrapping NTDLL.DLL functions. Some functions however need
+ assistance by the subsystem. For this reason the app makes an LPC to OS2SS.EXE.
+ LPC means local procedure call and it is a very fast version of RPC. Together
+ with the first application also OS2.EXE starts up. OS2.EXE runs in the win32
+ subsystem with the security of the current user. OS2.EXE is used to gather keyboard
+ and mouse input and to show console windows and PM-windows of all OS/2 programms
+ of the current user. In order to accomplish this OS2.EXE creates a port object
+ in the os2 object directory named Os2Interact. OS/2 applications have a connection
+ to OS2.EXE, too. OS2SS.EXE and OS2.EXE also talk to each other. An OS/2 application
+ then makes LPCs either to OS2.EXE directly or if required via OS2SS.EXE.</p>
+<p>Details</p>
+<p> </p>
+<p>LPC Documentation</p>
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+</html>