DOS Boot Sector
This is an x86 boot sector written in C. It is meant to bootstrap a DOS system on a FAT volume. A more detailed explanation of the code is available at https://crimsonglow.ca/~kjiwa/2010/09/dos-boot-sector.html.
View the source. It works like this at a high level:
- get the drive parameters
- load the contents of the root directory into memory
- look for IO.SYS in the root directory
- load the first 3 sectors of IO.SYS into memory and begin executing it
I've successfully compiled and tested it with the following tools:
- gcc 4.4.3
- binutils 2.20.1
- dosfstools 3.0.7
- bochs 2.4.2
The gcc and binutils host and target are both i386-pc-elf.
$ make boot # compile and link the boot sector $ make io # compile and link IO.SYS $ make disk # create a 10 MB disk image with a FAT volume $ make deploy # copy the boot sector and IO.SYS to the disk image