Monster Media 1993 #2/Image.iso/magazine/mpc93jun.zip/NDOS.TXT

Text File | 1993-05-30 | 11KB | 193 lines

     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!