B00ter

Boot sector programming, with the use of assembly x86.

Basic Programs

Check the directory ./basic for some simple programs and an introduction for boot sector programming.

Concepts include:

• BIOS services
• Memory mapped I/O
• Port I/O
• VGA

Booting

Here we get to load a program and pass control, to overcome the boot sector limits. We make use of BIOS services to read from a drive and load into memory.

Protected Mode

Check the directory ./protected_mode for the first steps into using the protected mode of the x86 architecture.

We then get to load a program like in the Booting section, but now in protected mode, this will allow us to start writing code in C.

Kernel

We can finally start our little 'kernel', we begin by implementing the bootloader that will load the kernel in protected mode, so that we can begin writing our kernel in C.

The main content of this project lies in ./kernel.

Resources

List of resources on the topic:

• Writing Boot Sector Code

• Writing a Bootloader from Scratch

• General Hardware Help and Reference

• Bios Interrupts Reference

• VGA - Video Hardware

• VGA - write modes

• I/O Ports list

• Intel 64 and IA-32 Architectures Software Developer’s Manual Combined Volumes

• Entering Protected Mode

• Global Descriptor Tables

• Using Inline Assmebly in C