NDOS  ?  
     by Chris Bieda

     Why You Should Delete   command.com  

     In the Beginning

     Sooner or later, every victim of the MS-DOS and PC-DOS operating 
     systems comes to learn that there are three essential files that 
     compose the core of the systems. (In MS-DOS, these are msdos.sys,
     io.sys and command.com; in PC-DOS, ibmdos.com, ibmbio.com and 
     command.com.) This knowledge usually is acquired shortly after the 
     user deletes  command.com  because it doesn't appear to do anything 
     useful, and besides, it's taking up disk space. (This is also the 
     point at which many users learn the expressions "bootable disk"   
     and "boot floppy.")                                

     The undaunted few proceed beyond this sobering experience to learn 
     what command.com actually does: it supplies the interface, a command 
     line, to DOS, as well as provides certain fundamental utilities, like   
     copy and rename, and delete and "dir." (The fact that command.com   
     accepts what you type to the command prompt and decides how to 
     handle it, either by processing the command itself, or loading 
     another program to do so, is why it is referred to as "the," or more 
     properly, if rarely, "a" command processor or command interpreter.)

     This ascension to the intermediate heights of power userdom is often 
     followed by the shocking revelation that command.com is, in fact, an  
     optional interface, at least insofar as you need not use command.com   
     if you have another command processor available!

     (Just as an aside, if there is reading this an OS/2 user who is not 
     familiar with DOS,  your cmd.exe serves the same purpose as DOS's 
     command.com, and it is just as optional!)

     Command Processor Options

     Besides DOS's command.com, there are two other options for command 
     processors that I know of (I would be glad to learn of others): the 
     JP Software company's 4DOS, a shareware program, and the Symantec 
     Corporation's  NDOS. In fact, these two programs are extremely 
     similar, largely because NDOS is a licensed OEM version of an 
     earlier release of 4DOS!  NDOS is supplied with version 6.xx of The 
     Norton Utilities, for many the indispensable set of DOS utilities, 
     and corresponds roughly to version 3.02 of 4DOS, which is currently 
     at version 4.01d.

     Since many of us own The Norton Utilities, and many more should, 
     I will describe cool features of NDOS  throughout this series. You 
     should note, however, that virtually everything I describe works 
     precisely the same way in the newer  4DOS  , and if you don't own the  
     Norton package, you can attain the same level of functionality by 
     using 4DOS (which is available from our BBS service, as well as our 
     public domain and shareware library service, Public Brand Software). 
     By the end of my tour, I suspect that quite a few of you will delete   
     command.com  one last time, because these optional processors are 
     great!             

     Compatibility Considerations

     Probably the coolest feature of NDOS is that it is fabulously 
     compatible. In fact, since booting to it for the first time over a 
     year ago, I haven't found a single application or utility, or DOS   
     routine, that gags or runs differently.                            

     This is no small feat, since there are literally dozens of books out 
     there with titles like Undocumented DOS or Secrets of the Command 
     Line Bill Gates Doesn't Want You To Know.  DOS, like any complex  
     operation (it is a system, after all), is full of bugs, leftover 
     code  (with leftover unintentional results) and back and trapdoors, 
     as well as undocumented or unsupported features. To successfully 
     support  Windows 3.x,  DESQview, and some of the worst-written TSR's 
     (terminate and stay resident, or "pop up," programs) ever, which were 
     written for command.com exclusively, NDOS must mimic the basic 
     operations of command.com almost perfectly. Based on my experience, 
     it does.      

     Installation

     A lesson many support personnel learn, often by painful trial and 
     error, is to get command.com tucked safely away in some place 
     that del-happy tyros won't easily find it (this is called "making 
     your life easier"). The traditional remedy has been to copy 
     command.com to a subdirectory, say the c:\dos subdirectory, and to 
     add the following line to the config.sys file in the root directory: 


     shell=c:\dos\command.com c:\dos /p   


     which instructs DOS to look for command.com in the specified 
     subdirectory at bootup, to look for a copy of command.com in c:\dos   
     when (if) it needs to load another, and (the "/p"  part) to leave 
     DOS running that particular processor ( c:\dos\command.com ) 
     when the bootup procedure is done. (It will also cause 
     c:\autoexec.bat to be run, which is most often a good thing!)

     Once these modifications were made (and with a bootable floppy at 
     the ready), c:\command.com was deleted, and the system rebooted 
     to look for, and use, the command.com tucked away. This often 
     solved the problem of del -zeal. (It remains recommended.)

     This same method is used to call NDOS instead of command.com, 
     to wit: 


     shell=c:\norton\ndos.com c:\norton /p   


     So much for installation.

     Making It All Pretty

     For real DOS-jockeys, the command-line, and not some fancy menuing 
     interface like Windows, GeoWorks or even  XTree, is the only way to 
     fly; it's certainly quicker, and "doing" the command-line marks you 
     as a real pro. It's what separates the adults from, say, Macintosh   
     users (just kidding folks). And for these people, the appearance of 
     their beloved DOS   "prompt" (the onscreen "message" displayed while  
     DOS awaits your next command) is critical. It must be useful, perhaps 
     fanciful, but certainly unique.

     Probably 95% of all DOS systems have a prompt that looks like "A" or 
     "C" or "A:\" or "C:\".   While these are useful (surely the latter 
     pair more than the former), they are not fanciful, nor unique.
     command.com gives you a handful of prompt customization options, but 
     NDOS supplies more, including perhaps the coolest prompt 
     feature imaginable, the (jargon-alert!) "shell nesting level."

     Back up a moment. The "shell," as you might have gathered by now, is 
     the context in which DOS software (applications and utilities) are 
     run.  It is established and maintained by the command processor 
     (whether command.com or NDOS), and a single context (instance of the 
     shell) is often all that a user, particularly one who works solely 
     within single applications (like 1-2-3 or WordPerfect) requires.

     Many users, however, use and enjoy a feature supplied by many 
     applications, commonly referred to as "shelling to DOS," or "opening 
     a DOS shell." These functions give the appearance of temporarily 
     exiting the application and returning to a point immediately before 
     the application was loaded, when the user was staring at a DOS prompt.

     In fact, this is an illusion. Far from exiting the application, 
     opening up a shell from within it temporarily suspends the 
     processing of that application (disconnecting it, as it were, from 
     the keyboard, display, disk drives, etc.), and opens up another 
     application:  the command processor.  

     You see, whether you are using command.com, ndos. com or 4dos.com, 
     you are already running a program (hence the ".com" for a  command 
     file), which is a command processor, or "shell." When you load  
     1-2-3 into that shell, you have now loaded  two   programs, the 
     second beneath the first. When you use that second program's 
     ability to "shell" to DOS, you open a third program (another shell), 
     and while in that second shell, you may even open a fourth, such as 
     a small utility program. God help you if that fourth program also 
     allows shelling to  DOS   (if you're keeping count, number five), 
     for if you do so, you may well get lost in your shells! This is 
     hazardous in the extreme when using  command.com-based shells, for t
     here is no simple way to tell if you are at the bottom of the "stack:"
     all the shells (command lines) look alike! (Several applications 
     modify    the prompt in the shells they spawn, to help clue you in,  
     e.g., "Type "exit" to return to WordStar.;" many simply do not.) 
     Should you shut your computer off (or should it lock up) while in a 
     "nested" (number two or subsequent) shell, all your work in the 
     applications resting below that was not saved before you went 
     shelling will be lost.  Scary stuff.

     NDOS enables a delightful prompt modification that can permanently 
     save your bacon. Putting the lowercase letter z into your prompt 
     string will imply the number of shells you have invoked by 
     displaying the sequence number of the one you are currently in, 
     starting with "0" (zero) for the first. So, for example: 

     prompt Level z [$p$g]   

     will return a prompt of "Level 0 [C:\]" when you are in the first 
     (primary) shell, "Level 1 [C:\]" when in the second, and so on. As a 
     result, when you are at any NDOS prompt, you know if there remain 
     matters beneath the current shell that require your attention. (At 
     Level 0, there is not; at other Levels, there are.) This is, of 
     course, no help whatever when the computer locks up in a secondary 
     or tertiary (or . . . ) shell, but when you are in control, you are 
     never blind.

     To be perfectly honest, so much do I use shells, and so few of these 
     shells provide customized prompts by themselves, that this one cool 
     feature would warrant my use of NDOS  over command.com.

     But there's more to  NDOS   than this, like faster batch file 
     processing, interactive batch files, and a   doskey   facility that 
     allows you to customize your environment to an amazing extent while 
     saving RAM!