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In this video we will set up the environment for the OS projects in Mac OS.

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The tools we need in the course are cross compiler, nasm assembler and bochs emulator. 

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As you see, this is the download link of the cross compiler.

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The version of the compiler is gcc 4.8.1 x86-64.

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The link is added to the external source of this lecture.

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You can download it using this link.

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After the package is downloaded.

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double click it 

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and you see the name of the package is gcc 4.8.1 linux x64. 

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Once we check the package is the correct one, we can install it.

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When the first time we run it, we could have this warning message.  In order to open it, we go to system preference panel

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,

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security and privacy 

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and click open anyway. 

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Ok now we can install the compiler. Click continue,  

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agree and then we get to the installation part. Click install and we are done. 

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Since it’s installed in my machine, I just exit out. 

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After the installation is done, we can check the status in the terminal.

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The path is usr local and the gcc we just installed. The command is located in the bin folder.

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As you can see, they are the commands we will use when we build the project.

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OK, what we are going to do next is we are going to install bochs emulator.

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All the projects will be tested in the emulator and then running in the real machine.

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The reason we need virtual machine is that when we put the project in the real machine, 

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the computer could restart if we have no interrupt handlers when the exception occurs. 

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Therefore, we tested the project in the virtual machine and then run the code in the real machine,

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if you like.

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And also, Bochs emulator can report error messages if the code causes exceptions, 

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which is especially important for us to debug the code.

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To install it, we type brew install bochs and press enter to finish the installation. 

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I have already installed the bochs, so I don’t run this command. 

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After you install it, you can check the status by typing bochs and press enter. You can see we have several options here. 

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We will discuss it in a minute. 

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Right now, we just choose seven and close it out.

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The next thing we are going to do is we are going to create an image file 

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since bochs will boot our projects with the image file. 

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First off, we navigate to desktop and the image will be created here. 

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To create the image file, we use command bximage. 

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We want to create hard disk image.

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so we select option 1 and hit enter. 

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The default setting is hard disk, we press enter.  Then we use the default settings as well. 

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Sectors is set to 512 bytes.  The size of disk is 10 megabytes which is enough for our project. 

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We name the image file boot.img and we will write the project into this image file and boot the computer. 

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Alright, the image file is created. Notice that we have these three values which we will need to fill in the bochs configuration file later

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OK

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at this point we can open bochs and edit the configuration file. 

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Because some options of the virtual environment configuration is not for our os projects.  

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We select option 3 to change some settings. 

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The first one we change is for the cpu features which is at option 6 cpuid options. 

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As you see, long mode support is enable and what we want is the 1g page support. 

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Our memory manager requires one gigabyte page support at the initialization stage, so we enable this

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feature.

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Then we return to the options menu.

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The memory allocated for the virtual machine is 1024 megabytes, which is enough for the product.

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In the memory options, we select standard options and we change the memory size to 1024. 

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Ok the last settings we need to change is for the boot image file. The option is 12 disk and boot options

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.

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we first look at channel 0. 

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You can see channel is enabled. And we use the default settings here. 

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Next we go to option 4 

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and we specify the type of device disk.  The file name is the name of the boot image file and press enter.

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We use the default mode.

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Remember we have seen the three numbers 20 16 and 63. 

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Here. They will be put into these settings. 

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As for other settings, we simply leave them unchanged. 

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Ok now the boot image will be loaded as a disk device. 

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Then we will select this device as the one booted first. So we change the floppy drive to disk. 

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That's it.

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We return to the top menu 

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and save options to the configuration file. 

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We exit it out and see what we have in the configuration file. 

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As you can see, the memory size is 1024mb. The boot option is set to disk. The disk path is boot.img. 

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We will place this file in the folder where we build the project. 

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And bochs will starts with the boot.img in the same folder.  We will delve into details when we build our first program.

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Another thing I need to mention is that since the gcc is installed in the customized path, 

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we need to run the command with full path. 

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You can check lecture how to use the resources in this section.

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Ok the next tool is nasm assembler, in the boot process of the operating system, 

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the assembly language is the only language we can use. 

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So we choose nasm assembler in this course. 

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To install nasm, we type brew install nasm and hit enter to install it. After you are done, 

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you can check it

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by the command nasm  -v.

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As for the text editor, I use visual studio code in the course. You can choose other ones you like. 

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If you choose visual studio code, I have added the link in the external source of the lecture.

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You can download it using this link.

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When you install it, you can add some extensions.

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The extensions I use are c extensions 

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and x86 64 assembly syntax highlighting.  Ok right now we have set up the environment.

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in the next section, we will start to build our operating system from scratch.

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Let's get started.