DOS Boot-up Sequence

IO.SYS: A hidden file in the root directory of the primary drive. This file provides the basic I/O capabilities for the system, allowing it the ability to communicate with the different peripherals. IO.SYS directs the overall process of loading the Operating System.

MSDOS.SYS: Also a hidden file in the root directory sometimes called the kernal for DOS. When an application needs to access a device or peripheral, this file translates the request into actions that IO.SYS can perform.

CONFIG.SYS: A user-configurable text file that usually contains device drivers and system setup values.

COMMAND.COM: This is the Command Interpreter. It can accept commands from the user, launch programs and pass this Information to MSDOS.SYS.

AUTOEXEC.BAT: Another user-configurable text file that is used to set system variables and load TSRs.