MS Dos Boot Files

The BIOS loads the Boot Code.
The Boot Code then looks for the three OS files

IO.SYS
MSDOS.SYS
COMMAND.COM

1.The Boot Code loads the IO.SYS
2.The IO.SYS loads the MSDOS.SYS
3.MSDOS.SYS loads the COMMAND.COM
4.COMMAND.COM looks for the configuration files CONFIG.SYS and AUTOEXEC.BAT if found, it loads them, if not it goes to the command prompt. ( C:\ )