Creating a native application for X86?

Is there a way I could make a C or C++ program that would run without an operating system and that would draw something like a red pixel to the top left corner? I have always wondered how these types of applications are made. Since Windows is written in 开发者_StackOverflow社区C I imagine there is a way to do this.

Thanks

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If you're writing for a bare processor, with no library support at all, you'll have to get all the hardware manuals, figure out how to access your video memory, and perform whatever operations that hardware requires to get a pixel drawn onto the display (or a sound on the beeper, or a block of memory read from the disk, or whatever).

When you're using an operating system, you'll rely on device drivers to know all this for you. Programs are still written, every day, for platforms without operating systems, but rarely for a bare processor. Many small MPUs come with a support library, usually a set of routines that lets you manipulate whatever peripheral devices they support.

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It can certainly be done. You typically write the code in C, and you pretty much have to do everything on your own, with no standard library. To set your pixel, you'd usually load a pointer to the physical address of the screen, and write the correct value to that pointer. Alternatively, on a PC you could consider using the VESA BIOS. In all honesty, it's fairly similar to the way most code for MS-DOS was written (most used MS-DOS to read and write data on disk, but little else).

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The core bootloader and the part of the Kernel that bootstraps the OS are written in assembly. See http://en.wikipedia.org/wiki/Booting for a brief writeup of how an operating system boots. There's no way I'm aware of to write a bootloader or Kernel purely in a higher level language such as C or C++ without using assembly.

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You need to write a bootstrapper and a loader combination followed by a payload which involves setting the VGA mode manually by interrupt, grabbing a handle to the basic video buffer and then writing a value to the 0th byte.

Start here: http://en.wikipedia.org/wiki/Bootstrapping_(computing)

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Without an OS it's difficult to have a loader, which means no dynamic libc. You'd have to link statically, as well as have a decent amount of bootstrap code written in assembly (although it could be provided as object files which you could then link with). Also, since you'd be at the mercy of whatever the system has, you'd be stuck with the VESA video modes (unless you want to write your own graphics driver and subsystem, which you don't).

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There is, but not generally from within the OS. Initially, they are an asm stub that's executed from the MBR on the drive. See MBR. For x86 processors, this is generally 16-bit processing code, this generally jumps into the operating system code from here, and upgrades to 32-bit/64-bit mode depending on the operating system and chipset.