When DOS boots up, it looks in the root directory of the boot disk for a
 text file named CONFIG.SYS.  If that file exists, it is read and processed
 as a list of configuration commands.

  Command     Function                 Command   Function
  BREAK=      Ctrl-Break test level  █ INSTALLHIGH= load TSRs into UMB
  BUFFERS=    # of disk I/O buffers  █ MENUITEM=    menu text & action
  COUNTRY=    country-dependant info █ MENUCOLOR=   menu colors
  cmd?=       conditional execution  █ MENUDEFAULT= default and time-out
  DEVICE=     install device driver  █ NUMLOCK=     state of NumLock
  DEVICEHIGH= install driver in UMB  █ REM or ;     comments in CONFIG.SYS
  DRIVPARM=   parms for disk drivers █ SET          e-vars in CONFIG.SYS
  FCBS=       max open FCBs          █ SHELL=       install cmd processor
  LASTDRIVE=  SUBST drive ID limit   █ STACKS=      hdwr int stack sizes
  FILES=      max # of file handles  █ SUBMENU=     set up a submenu
  INCLUDE=    run cmds in a block    █ SWITCHAR=    cmd-line switch char
  INSTALL=    load TSRs              █ SWITCHES=    kydb, boot opts, etc.

 CONFIG.SYS is a standard text file, created by any text editor.  Changes
 to CONFIG.SYS take effect only after you restart DOS.

See Also: Enhanced CONFIG.SYS Options
          MultiConfig Menus
          Device Drivers
          System Startup Sequence