MS DOS 6.0 introduced the ability to specify multiple configurations in the config.sys and autoexec.bat. This feature can be used for different situations:

• Dual boot situation with the option to either boot in DOS with all device drivers loaded (CDROM etc.), or to boot in Windows 95 where it should not load any DOS device drivers.
• Different memory configurations whether to have lots of conventional memory or expanded memory.
• Starting DOS with or without support for network or CDROM drives.

This is a simple config.sys, which tries to outline the basics of multiple configurations with the use of MENU and MENUITEM:

[MENU]
REM Define an item in the menu, first identifier and then what is written in the menu
MENUITEM=DOS, DOS with CD-ROM
MENUITEM=WIN, Windows
 
REM The commands at COMMON is executed no matter what is chosen in the MENU
[COMMON]
DOS=HIGH,UMB
 
REM For each menu item there can be defined a configuration
[DOS]
DEVICE=C:\DOS\HIMEM.SYS /TESTMEM:OFF
DEVICE=C:\DOS\EMM386.EXE NOEMS
DEVICE=C:\CDROM\DRIVER.SYS /D:CD1
 
[WIN]
DEVICE=C:\DOS\HIMEM.SYS /TESTMEM:OFF

This is a simple autoexec.bat, where the MENUITEM is translated into the environement variable CONFIG:

@ECHO OFF
PROMPT=$P$G
SET DIRCMD=/A/OGN/P
 
REM Uses the identifier from CONFIG.SYS to goto a label
GOTO %CONFIG%
 
REM This is the label for the identifier DOS
:DOS
LH C:\DOS\MSCDEX.EXE /D:CD1
LH C:\DOS\SMARTDRV.EXE 2048
 
REM The GOTO EXIT is required so it won’t continue into the WIN configuration
GOTO EXIT
 
REM This is the label for the identifier WIN
:WIN
 
REM The ECHO command writes a message on the DOS screen
ECHO Starting Windows…
 
C:\WINDOWS\WIN
 
:EXIT

It is possible to extend menu-system in the config.sys with SUBMENU, which enables sub-menus. One can also use MENUDEFAULT to specify the default menu item and how long it should wait before it picks the default.

  [MENU]
  MENUITEM=DOS, DOS with CD-ROM
  MENUITEM=WIN, Windows

  REM By using SUBMENU you will creating an extra menu(TEST)
  SUBMENU=TEST, Testing

  REM Using MENUDEAFAULT makes it possible to choose a certain
  REM item(WIN) and if it’s set also select that item after a certain
  REM time(20 secs)
  MENUDEFAULT=WIN, 20

  REM Here is the SUBMENU it can also include other SUBMENUs
  [TEST]
  MENUITEM=TEST1, Testing 1

To read more about multi-configurations menus execute the following command:

  help multi-config