MS-DOS / PC DOS and some related disk operating systems use the files mentioned here.

System Files:^[1]

• IO.SYS (or IBMBIO.COM): This contains the system initialization code and builtin device drivers;
• MSDOS.SYS (or IBMDOS.COM): This contains the DOS kernel.

Command-line interpreter (Shell):

• COMMAND.COM: This is the command interpreter.

User configuration files:

• AUTOEXEC.BAT: This is run by the default shell (usually COMMAND.COM) to execute commands at startup.
• CONFIG.SYS: This contains statements to configure DOS and load device drivers.

Standard DOS utility programs:

• APPEND: Set a search path for data files.
• ASSIGN: Redirect requests for disk operations on one drive to a different drive.
• ATTRIB: Set or display file attributes.
• BACKUP / RESTORE: simple backup and restore utilities.
• CHKDSK: Check disk for file system integrity.
• COMP: File compare utility.
• DEBUG: Simple command line debugger.
• DELTREE: Delete a directory tree.
• DISKCOMP: Compare floppy disks.
• DISKCOPY: Copy floppy disks.
• DOSKEY: Command line editor.
• EDIT / EDLIN: Very basic text editor(s); EDLIN is in earlier versions.
• FC: File compare utility.
• FDISK: Partitions fixed disks.
• FIND: Find text in files.
• FORMAT: Formats disks.
• JOIN: Joins a drive letter to a subdirectory.
• LABEL: Set or remove a disk volume label.
• MEM: Display memory usage.
• MODE: Set modes for system devices.
• MORE: Display output one screen at a time.
• MOVE: Move files from one directory to another.
• PRINT: Print spooler.
• REPLACE: Replace files.
• SHARE: File sharing and locking support.
• SORT: Sorts input.
• SUBST: Substitutes a drive letter for a subdirectory.
• SYS: Transfers the system files to another drive to make it bootable.
• TREE: Display a directory tree.
• XCOPY: Extended file copy.

Standard DOS device drivers:

• ANSI.SYS: ANSI console driver.
• EMM386.EXE: Expanded memory manager.
• HIMEM.SYS: Extended memory manager.
• RAMDRIVE.SYS / VDISK.SYS: RAM disk; VDISK.SYS is in older versions of PC DOS.

References