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.

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The CONFIG.SYS File