https://github.com/kjiwa/x86-boot-sector-c

A DOS boot sector written in C
https://github.com/kjiwa/x86-boot-sector-c

Last synced: 3 months ago
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A DOS boot sector written in C

• Host: GitHub
• URL: https://github.com/kjiwa/x86-boot-sector-c
• Owner: kjiwa
• Created: 2015-03-05T20:24:15.000Z (over 9 years ago)
• Default Branch: master
• Last Pushed: 2018-12-25T01:36:30.000Z (almost 6 years ago)
• Last Synced: 2024-07-17T18:54:59.880Z (4 months ago)
• Language: C
• Homepage: https://crimsonglow.ca/~kjiwa/2010/09/dos-boot-sector.html
• Size: 16.6 KB
• Stars: 26
• Watchers: 4
• Forks: 7
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# 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](boot.c) 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.

```shell

$ 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

```

##### External Links #####

* [SYS.COM Requirements in MS-DOS versions 2.0-6.0](http://support.microsoft.com/en-us/kb/66530/en-us)

* [int 13](http://www.ctyme.com/intr/int-13.htm)

* [Memory Map (x86)](http://wiki.osdev.org/Memory_Map_%28x86%29)

* [File Allocation Table](http://en.wikipedia.org/wiki/File_Allocation_Table)