The DOS control can be explained in the following steps:

★ The first step the boot loader loads the boot record to the memory, which is given the control ( boot program ) inside the boot record.

★ This program now check for the IO.SYS and MSDOS.SYS as the first entries.

★ Now the program loads the IO.SYS and is given control.

★ The IO.SYS simply loads the MSDOS.SYS file and starts looking for the CONFIG.SYS file .

★ Finally the MSDOS.SYS file is given control, this file now initializes interrupt vectors and loads the COMMAND.COM file.

★ Lastly the autoexec.bat file is loaded, executed.