Source : Free On-Line Dictionary of Computing

CONFIG.SYS
     
         A {text file} containing special system
        configuration commands.  It is found in the {root directory}
        on an {MS-DOS} computer, typically on {drive} C (the {hard
        disk}).  It is read by {MS-DOS} at {boot time}, after the
        setup has been read from {CMOS RAM} and before running
        {AUTOEXEC.BAT}.  It can be modified by the user.
     
        Some example commands which CONFIG.SYS might contain are:
     
        	DEVICE=C:\DOS\HIMEM.SYS /testmem:off
     
        Load the {extended memory} manager.
     
        	DEVICE=C:\DOS\EMM386.EXE RAM
     
        Load the {expanded memory} manager.
     
        	BUFFERS=10,0
     
        Specify memory for {disk buffer}s.
     
        	FILES=70
     
        Set the number of files that can be open at once.
     
        	DOS=UMB
     
        DOS is located in {UppeMemoryBlock}.
     
        	LASTDRIVE=Z
     
        Disk drives are A: to Z:.
     
        	FCBS=16,0
     
        Set the number of {file control block}s.
     
        	DEVICEHIGH /L:1,12048 =C:\DOS\SETVER.EXE
     
        Report the DOS version to older programs.
     
        	DOS=HIGH
     
        DOS should maintain a link to {UMB}.
     
        	COUNTRY=358,437 C:\DOS\COUNTRY.SYS
     
        Set the {country code} for some programs.
     
        	STACKS=9,256
     
        Set {dynamic stack}s for hardware control.
     
        	SHELL=C:\DOS\COMMAND.COM C:\DOS\ /E:1024 /p
     
        Set the location of the {command interpreter}.
     
        (1995-03-16)