MS-DOS 6. (IBM's operating system) (Software Review) (Evaluation)
by Mark Minasi

MS-DOS 6 is the latest version of Microsoft's best-selling operating system. The DOS 6 features that you probably haven't heard much about are, strangely, the ones that make the upgrade worthwhile. There's a lot to like in DOS 6.

Probably the most useful new feature is MultiConfig. If you have one CONFIG.SYS (and AUTOEXEC.BAT) for your normal work, another one that you use sometimes when you need the most free memory, another that's completely vanilla, and perhaps one other to play Wing Commander II, then you have to have MultiConfig. There are boot manager programs, but they always seemed to give me heartburn when I used them with OS/2 or NT

In contrast, MultiConfig is a fairly simple program that's built into the operating system. It lets you put a pile of configurations into a single AUTOEXEC.BAT/CONFIG.SYS, and two keystrokes let you choose a specific setup that's right for today. Best of all, it coexists with other operating systems with no muss, fuss, or greasy aftertaste. So I call MultiConfig the best single reason to buy DOS 6.

But that's not all there is to this upgrade. The memory manager is better, although it isn't perfect (yet). The EMM386.EXE/HIMEM.SYS two-part memory manager shipped with DOS 5 is a good basic memory manager. It's particularly well adapted to working with Windows, and it can accomplish about 90 percent of what a full blown memory manager like QEMM-386 or 386Max can do. DOS 5's memory manager really lacks only two important tools: program placement and program squeezing. On that front, when we look at DOS 6, there's some good news, and there's some bad news.

Program placement makes it possible to say to the memory manager, "Not only do I want to load this program high - into an upper memory block - but I also want to load it to this particular location." DOS 5 can't do this, but DOS 6 can. That's the good news.

But what about program squeezing? Program squeezing is necessary when you're trying to load a program that seems very large when it begins loading but then settles down to a small memory footprint. Such a yo-yo program can cause a memory manager to erroneously refuse to load the program high. What happens is that the memory manager sees the program in its initial huge configuration and reckons that a program that large will be unable to fit into the upper memory area. As a consequence, the memory manager loads the program into low memory.

A squeeze feature allows you to inform your memory manager that a program is a yo-yo. Duly informed, the memory manager will exercise a little patience and load the program high on the basis of its final load size, not on its overstated initial load size. Other memory managers have this capability, but - here's the bad news - DOS 6 doesn't. Maybe next time?

Next on the list of new features is Interlnk. If you travel, you'll appreciate interlnk. I travel all the time, so there are few weekdays that I'm writing with my desktop machines. Sunday through Thursday nights, I bang out PC prose on my notebook. And when I return home, I want to easily move the fruits of my labors to one of my desktop machines. But shuffling floppies around is a pain. I've tried Lap-Link - all the pundits say that it's the best - but I find its menus confusing. DOS 6's serial/parallel file transfer program, Interlnk, is exactly what I've been looking for.

Interlnk lets me connect two machines parallel port to parallel port and load a device driver. Then one of the machines acts like a LAN server. I had an extra parallel port, so I installed it in my desktop machine as LPT2 and put a parallel transfer cable on it. Now, when I come home, I just plug the other end of the cable into the parallel port on my notebook computer, run Interlnk (I don't even have to mess with CONFIG.SYS - I have MultiConfig set to offer an Interlnk optional setup), and voila! My notebook computer now has a new drive, E. Drive E is, of course, really drive C on my desktop machine. An Xcopy command or two, and my data's transferred.

I find the new DOS online help to be of great value when I'm editing a CONFIG.SYS file. (What were those Interlnk parameters, anyway?) And while I've always had virus scanner programs around, DOS's built-in virus scanner is OK. That means that carrying DOS disks around with me will serve the virus-scanning function, allowing me to carry fewer disks.

Up through DOS 5, batch files could talk, but they couldn't listen. However, that's no longer true. There's a new batch command called CHOICE, which allows your batch files to prompt for single-character answers. Furthermore, the CHOICE command can be used in a timer role. You can use CHOICE as a kind of poor man's time activator.

Undeletion capabilities appeared in DOS 5, but DOS 6 takes undeletion a step further in reliability with a feature called Delete Sentry. Once activated, Delete Sentry prevents DOS from actually erasing files when you issue a Del or Erase command. Instead, DOS moves the files to a hidden directory. It holds them there for a while (you can define a while however you like), which gives you a chance to change your mind and restore the files later.

DOS 6's new features bring with them some opportunities for trouble, as is the case with all new pieces of software. In particular, you may want to be careful about installing Doublespace, the new disk compression routine. If you do plan to use DoubleSpace, try doing a few things to minimize the chance that you'll stumble on the path to more disk space. First, prepare your disk before installing DoubleSpace (it isn't installed automatically; you install DOS 6 and type dblspace when you're ready to start using this feature).

Doublespace has a hard job, so it's a good idea to make the job as easy as possible for it. Clean your disk by getting rid of any extra disk files; get rid of anything that you haven't used in a while. Then defragment your disk with the new Defrag command. Finally, do not compress the entirety of your C drive; instead, let DoubleSpace create a new drive out of the empty space on your C drive. If you find it necessary, remove some things from C, create a new drive from the empty space, and then restore the files to the new drive. Be aware that the new SMARTDrive requires that you reboot your system by executing a Ctrl-alt-delete keystroke combination - don't use your reset switch! Keep that in mind, and you'll be able to get up and running with more disk space in short order.

DOS 6's MemMaker will organize your memory manager to give you more memory, and you will probably want to run it soon after installing DOS 6. But heed one word of advice: Don't run Express Setup. Run Custom Setup instead; you'll eventually see the question Search upper memory aggressively? Respond by answering no; then let 'er rip! You may find yourself with more RAM than ever before. (All of a sudden, running Wing Commander with the sound effects becomes possible.)

DOS 6 is a good buy; it's an even better buy if you take a close look at some of its less publicized features. If you didn't go for this upgrade when it was offered at a special introductory price, don't feel too bad. At least you can still get it-and the new utilities bundled with it definitely justify the cost.