OVERVIEW

1. Get deep understanding of INTEL 8086 architecture
2. Build a micro OS kernel including
   • FAT12 Filesystem support
   • Process Management (PM) with Multi-Task support
   • System call support

ROADMAP

1. Understanding BOOT procedure of 8086 system (FLOPPY only!)
   • Creating DEV environment -- QEMU, an emulator that can provides virtual environments of 80386, x86_64, ARM, MIPS, SPARC, etc.
2. Getting familar with INTEL 8086 ISA
   • Read INTEL 8086 Manual
   • Download & Install NASM
   • Read NASM's manual
3. Understanding FAT12 specifications
   • Create a virtual floppy image (boot.img, source: boot.nasm)
4. Build a bootloader of our future OS
   • Understanding the limit of floppy boot: code size limit of 512B
   • BootLoader construction process:
     • Search KERNEL.BIN in RootDirSectors
     • Read File Allocation Table (FAT) for details
     • Loading KERNEL.BIN using BIOS INT (0x13)
     • Transfer control to KERNEL.BIN
5. Build KERNEL.BIN

   • Download Bruce's C Compiler (bcc)

       bcc -0 -ansi -c source.c   
           -0:     generating 8086 (16bit) code    
           -ansi:  support ANSI C    
           -c:     compile only    
     
       ld86 -d -M source.o -o source.bin   
           -d:     generate flat binary file    
           -M:     print organization    
           -o:     target file    
     

     See manuals for details of bcc, as86, ld86.

   • Build a simple process management system

     • Task scheduling subsystem (supporting multiprocesses)
     • A basic IPC subsystem (PV operators && resources)

   • Write a simple SHELL process dealing with I/O
     TIPS: Library functions (e.g. strcmp) can be linked to target image

HOW TO RUN

1. Install QEMU & BCC (including bcc, as86 and ld86)
2. make
3. Put os.bin to boot.img (e.g. under Linux).
   • mkdir /mnt/floppy/
   • mount -o loop boot.img /mnt/floppy/
   • cp os.bin /mnt/floppy/
   • umount /mnt/floppy/
4. qemu -fda boot.img