These are very useful for writing batch files which can make 
life at the DOS level a little easier.

ANSI       screen driver for Portfolio    
ASK        displays a prompt, clears the kbd buffer then waits for a keypress   
ATTRIB     displays or sets the attributes of files   
BEEP       generate tones for a period of time   
CMDEDIT    buffers mand history which you can edit   
DIF        pares text between two files.   
DSKCHK     checks the disk's structure for corrupted clusters   
FIND       searches each file for specified text   
FM         File Manager DOS shell
FREEDSK    displays the amount of free space and returns ERRORLEVEEL   
FREEMEM    Amount of free space in the largest block of memory.   
KSIM       provides keypress to the O.S. from an object file from KSIMP  
KSIMPCOM   Compiles text which describes keystrokes
MODE       select Setup options from a batch file   
PASSWORD   Control access to your CCM     
REBOOT     warm or cold reboot    
SORT       Sort a text file
SPOOL      Install print spooler      
TOD        time of day and sets errorlevel for country 
UPDATE     update internal software   
XCOPY      enhanced copy recognizes subdirectories  
XDIR       extended version of dir  display contents of dirs and subdirs  
XTERM      xmodem terminal