Basic steps for making a bootable MS-DOS disk

1) setup the partition

use GParted to:

1. make sure the partition is formatted as FAT16, or as FAT32 (required for >2GB partitions)
2. enable the BOOT FLAG
3. enable the LBA FLAG (required for >504MB partitions)

2) write boot sectors (with ms-sys)

Note that for partitioned drives, you have to write TWO chunks of bytes: the MBR, and VBR. For unpartitioned drives (or partitions that you'll boot with a chainloading bootloader), you only need the VBR.

These are the combinations that have worked for me so far:

3) copy bare-minimum files over

• io.sys (but if you're just copying it over, you MUST use MS-DOS v7.x; earlier versions required io.sys to be the first file on the disk [the first FAT entry], which requires sys.com to do)
• msdos.sys
• command.com

4) copy over additional files to taste

Autoexec.bat and config.sys are most helpful.

Logo.sys can be added for good looks.

You can copy over the full install of MS-DOS. For v7.10, these files are:

ados.com  append.exe  attrib.exe  bdrv.exe  chkdsk.exe  choice.com  command.com  compress.exe  ctmouse.exe  cvt.exe  debug.exe  deltree.exe  diskcomp.com  diskcopy.com  doshelp.com  doskey.com  doslfn.com  dosshell.com  dosshell.exe  dosswap.exe  edit.com  edlin.exe  emm386.exe  exe2bin.exe  expand.exe  extract.exe  fakemous.com  fasthelp.exe  fastopen.exe  fc.exe  fdisk.exe  find.exe  format.com  graphics.com  keyb.com  killer.exe  label.exe  lmod.com  loadfix.com  mem.exe  memmaker.exe  mklink.exe  mode.com  more.com  move.exe  mscdex.exe  msd.exe  nlsfunc.exe  power.exe  print.exe  qbasic.exe  recover.exe  replace.exe  scandisk.exe  setver.exe  share.exe  shutdown.com  sizer.exe  smartdrv.exe  sort.exe  subst.exe  sys.com  tree.com  vsafe.com  xcopy.exe 

5) test that it works under QEMU

qemu -hda /dev/sda

External links

• The DOS boot process
• Detailed notes on SYS.COM