mirror of
https://github.com/danbulant/Cosmos
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199 lines
11 KiB
HTML
199 lines
11 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml" >
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<head>
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<title>Untitled Page</title>
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</head>
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<body>
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<h3>
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Cosmos?</h3>
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<p>
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Cosmos is short for C# Open Source Managed Operating System. Despite C# being in
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the name, VB.NET, Fortran, and any .NET language can be used. We chose the C#
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title because our work is done in C#, and VBOSMOS just does not sound as nice.</p>
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<p>
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Cosmos is not an operating system in the traditional sense, but instead it is
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"Operating System Kit", or as I like to say "Operating System Legos", that allow
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you to create your own operating system. However having been down this path
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before, we wanted to make it easy to use and build. Most users can write and
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boot their own operating system in just a few minutes, and using Visual Studio.</p>
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<p>
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Cosmos lets Visual Studio compile your code to IL and then Cosmos compiles the
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IL into machine code.</p>
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<h3>
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Dev Kit or User Kit?</h3>
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<p>
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Cosmos comes in two flavors, a user kit and a dev kit. The user kit hides the
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kernel source away from the user and presents a new project type in file, new.
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Building a new operating system is as simple as file, new, writing a few lines
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of code and pressing F5 to build and run it. The user kit is a bit old though,
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and is really only designed to interest people in obtaining the dev kit.</p>
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<p>
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The dev kit is available as a project on <a href="http://www.CodePlex.com/Cosmos/">CodePlex</a>, and the Cosmos website
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is <a href="http://www.GoCosmos.org">www.GoCosmos.org</a>..</p>
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<h3>
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Dev Kit</h3>
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<p>
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To get the dev kit simply sync the sources from the CodePlex project. It might
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appear daunting at first, 43 projects? A lot of these projects are demos, tests,
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and playgrounds.</p>
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<p>
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Note that Visual Studio Express cannot handle the solution folders. Because of
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this Express users should use the Flat solution file, but first you must update
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the Flat solution file from the main solution using the Flat file updater
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utility.</p>
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<p>
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<img alt="" src="SNAG-0000.jpg" style="width: 203px; height: 178px" /></p>
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<p>
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In the Boot folder, and then the Demo folder you will see a CosmosBoot project.
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This is the empty shell used in the User Kit for the new project template. This
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is the minimal Operating System that Cosmos can build. You can copy this file
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and change it to your needs. Let's take a quick look.</p>
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<p>
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<img src="SNAG-0001.jpg" style="width: 138px; height: 74px" /></p>
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<p>
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Properties and References are standard parts of any .NET project. Let's look in
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Program.cs<p>
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Note on images: CodeProject limits images to 600 pixels in width. I've chosen to
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crop the width to retain readability.<p>
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<img src="SNAG-0002.jpg" style="width: 700px; height: 339px" /></p>
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<p>
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Init is the entry point that will be called after the system is booted. This is
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where you put your code. Some sample code has been generated already and you can
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change it. Be sure to leave the first two lines alone, they initialize memory,
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hardware, etc.</p>
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<p>
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Let's take a look at something a little more complex though. Here is a demo
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called Guess. It is a simple application which asks the user to guess a number.
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As you can see, it is all standard C# code, and aside from the first two lines
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for booting the code can function unchanged on Windows.</p>
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<p>
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<img src="SNAG-0004.jpg" style="width: 661px; height: 459px" /></p>
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<p>
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NNow let's run it. Are you expecting some complicated process involving batch
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files and CD-R's? If so you will be disappointed. Simply press F5 in Visual
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Studio to run it. Instead of the project running immediately, you will see a
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Cosmos Builder Options window.</p>
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<p>
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<img src="SNAG-0007.jpg" style="width: 452px; height: 663px" /></p>
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<p>
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The builder support many environments including physical hardware. Virtual
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Machines are easier to develop against, and are certainly easier to take
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screenshots of so I will use VMWare for this article.
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</p>
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<p>
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With these options set, I clicked the Build button (The Enter key also
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proceeds). Next a build progress window will appear. Cosmos is now compiling the
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IL to machine code, linking and preparing the boot image.</p>
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<p>
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<img src="SNAG-0011.jpg" style="width: 300px; height: 300px" /></p>
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<p>
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When this is done, the window will disappear and VMWare will automatically be
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launched with an ISO mounted./p>
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<p>
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<img src="SNAG-0012.jpg" style="width: 637px; height: 518px" /></p>
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<p>
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Select "Power on this virtual machine" and the Guess demo will boot.</p>
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<p>
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<img src="SNAG-0014.jpg" style="width: 743px; height: 551px" /></p>
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<p>
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TThis is the demo, booted directly to hardware. There is no need for Windows,
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Linux or any other operating system to run this code. During the boot process
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you may notice SysLinux. SysLinux however is not a Linux distribution, but
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instead just a boot loader used to read files from the disk. We use SysLinux
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instead of Grub because it has support for PXE and other options. SysLinux is
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only used for initial loading of the Cosmos binaries and as soon as Cosmos is
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loaded SysLinux is unloaded is not used to run Cosmos code.</p>
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<h3>
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Graphics, Network, File Systems/h3>
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<p>
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Ease of use, or what I like to call "Nail the basics" is a priority for us.
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However graphics and other things will follow in the future. Currently we are
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working on a wide range of file systems including FAT and ext2. We are also
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working on Ethernet support and can already send basic UDP packets, and are
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working on TCP support as well.</p>
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<h3>
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DDebugging</h3>
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<p>
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Debugging operating systems is typically inconvenient and hinders progress.
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Because of this, just as we did with making the build and boot process, we
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strived to make the debugging process easy. The debugger is still a work in
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progress, but is already quite advanced for an operating system debugger.</p>
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<p>
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<img src="SNAG-0018.jpg" style="width: 268px; height: 85px" /></p>
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<p>
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Adding the Cosmos.Debug namespace gives the code access to communicate directly
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with the debugger.</p>
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<p>
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<img src="SNAG-0022.jpg" style="width: 294px; height: 161px" /></p>
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<p>
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In the Guess demo I am adding a Debugger.Send, which will write a debug string
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to the debugger. These can be used to track code execution, but can also be used
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for watching variables. In this case I will use it to write out the magic
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number.</p>
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<p>
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<img src="SNAG-0023.jpg" style="width: 347px; height: 125px" /></p>
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<p>
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Notice I have also added a Debugger.Break. This will force the program to
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execute a breakpoint at that location.</p>
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<p>
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Now let's run the Guess again. Which demo is booted is selected in Visual Studio
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simply by selecting it as the startup project for the solution.</p>
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<p>
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<img src="SNAG-0024.jpg" style="width: 253px; height: 100px" /></p>
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<p>
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This time in debugger options Source and User Only is selected. Source tells the
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debugger to debug C# code, rather than the lower level IL. And User Only tells
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the debugger not to trace into the Cosmos Kernel or the .NET libraries. This
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speeds up execution, but also lets me focus on tracing just the demo code.</p>
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<p>
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<img src="SNAG-0025.jpg" style="width: 743px; height: 551px" /></p>
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<p>
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Note that this time it did prompt us for the number yet? This is because it hit
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the breakpoint. Another window will appear as well, this is the Cosmos Debugger.</p>
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<p>
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<img src="SNAG-0026.jpg" style="width: 720px; height: 379px" /></p>
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<p>
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The message and breakpoint are displayed in the trace log, and the code is
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selected for the breakpoint. Breakpoints occur on the next statement after the
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requested break.</p>
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<p>
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Now we can use the Step button (F11, just like Visual Studio) to step through
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the code. Each step is recorded in the trace log and previous items can be
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selected to walk backwards through the code. The trace log functions similarly
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to the call stack window in Visual Studio.</p>
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<p>
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<img src="SNAG-0027.jpg" style="width: 683px; height: 460px" /></p>
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<p>
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Press continue (F5) and the code will run again until a breakpoint is
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encountered in code, or requested from the debugger. After continue, a new
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button will appear to that allows a forced instant break. After continue, the
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code will continue and we will be prompted for the number.</p>
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<p>
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<img src="SNAG-0028.jpg" style="width: 743px; height: 551px" /></p>
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<p>
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We can also turn tracing on and off for specific sections of code using the
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Cosmos.Debug namespace.</p>
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<p>
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<img src="SNAG-0029.jpg" style="width: 335px; height: 225px" /></p>
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<p>
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This will cause the trace log to be populated with all statement executions
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between the TraceOn and TraceOff without needing to step through each statement
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manually.</p>
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<p>
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<img src="SNAG-0030.jpg" style="width: 255px; height: 94px" /></p>
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<p>
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This time Cosmos & User is selected to show more details in the trace log.
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Normally this option is only needed by developers working on Cosmos kernel
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source.</p>
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<p>
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<img src="SNAG-0031.jpg" style="width: 764px; height: 559px" /></p>
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<h3>
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Conclusion</h3>
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<p>
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Cosmos is an open source project as included as part of its name. I hope this
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article gives an easy to understand introduction. If you are interested in
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operating system development I hope you will try Cosmos!</p>
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</body>
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</html>
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