http://www.chami.com/tips/windows/122096W.html

CMD.EXE or COMMAND.COM

Windows NT comes with two "command line shells" -- one called CMD.EXE and the 
other called COMMAND.COM. If you're wondering which one to use, following 
information might help:

CMD.EXE is the Windows NT's native command prompt (or shell), which means it 
is more portable among different hardware platforms. For example, if you type 
SET and press ENTER inside a CMD.EXE prompt, you'll notice that CMD.EXE 
exposes more environment variables than COMMAND.COM. On the other hand, 
COMMAND.COM is the more "MS-DOS compatible" version of the two shells. For 
example, this shell will call AUTOEXEC.NT and CONFIG.NT (located in the 
SYSTEM32 directory inside your Windows NT directory) just like MS-DOS used to 
call AUTOEXEC.BAT and CONFIG.SYS.

So, if you're having trouble running your old DOS command line programs from 
Windows NT, try running them inside a COMMAND.COM shell, not CMD.EXE.


==> Start
    ==> Help & Support [click]
        ==> Search [command-line]
            Command-line reference A-Z
        ==> Search [Command shell overview]
            Command shell overview
            Concepts
        ==> Search [Using batch files]
            Batch files
            - Call             - Rem
            - Echo             - Endlocal
            - For              - Setlocal
            - Goto
            - If
            - Shift
            - Pause