Classic Computer Magazine Archive COMPUTE! ISSUE 133 / SEPTEMBER 1991 / PAGE 56

DOS 5.0, a perfect 10: the software bargain of the year. (includes related articles) (evaluation)
by Mark Minasi

Since its introduction ten years ago, DOS has seen a lot of changes, not all for the better. People with long PC experience and good memories know that new versions of DOS are often mixed blessings, so the news that there's a new version may not bring a smile to everyone's face.

But this version is different, and it ought to make you smile. With version 5.0, DOS has emerged from its stormy adolescence and developed into a mature, well-rounded operating system.

What's so special about this DOS? Well, it uses less memory than previous versions and includes commands that allow you to unerase files and, more amazing, unformat disks.

It comes with a shell that lets you run multiple programs at the same time, and it remembers your last 20 or so commands, allowing you to recall, edit, and reissue them, saving countless keystrokes.

With the new DIR command, you can sort files by name, size, date, or extension; show hidden files; only show hidden files or files that haven't been backed up; and a multitude of other possibilities.

If I sound breathless, I am. I've worked with enough so-called new-and-improved software products to know what to expect of a new operating system. I figured that 5.0 either wouldn't work with my Novell network, would clask with my OnTract Disk Manager, or wouldn't run with Windows, and on and on.

Imagine my surprise when I saw that 5.0 ships with a Novell driver, a 5.0-compatible version of the OnTrack software, and new and cleaner versions of EMM386.EXE and HIMEM.SYS, the critical memory-organizing device drivers used by Windows 3.0!

Microsoft has really put some thought into this system, and I'm sure it's going to pay off. I wouldn't be surprised if virtually everyone in the PC world hasn't switched to DOS 5.0 within a year.

More Memory

At a recent press conference, a Microsoft PR person asked, "What is Microsoft best known for?" A member of the audience shouted, "The 640K limitation!"

That wasn't the answer the flack was looking for, but it addressed perhaps the best-known and most annoying limitation of MS-DOS. The operating system is restricted to using the lowest part of your computer's memory potential, called conventional memory.

Some vendors have responded to this problem with clever programs called memory managers. The best-selling of these are QEMM, from Quarterdeck Systems, and 386MAX, from Qualitas. These programs allow you to make some use of the extended memory that often goes unused on a 386, 386SX, or 486 system. These 386-type systems can theoretically have more than 4000 megabytes of extended memory, so any program that lets you use some extended memory is obviously valuable.

These memory managers perform two main functions. First, they allow you to load device drivers and memory-resident TSR programs above the 640K of conventional memory, freeing up conventional memory that was once used by these helpers.

Second, they temporarily translate some of that otherwise-unused extended memory into a third kind of memory called expanded memory, memory used by programs like 1-2-3 version 2 or WordPerfect version 5.1.

Both of these functions are valuable, and that's why both Qualitas and Quarterdeck sales are doing well at the moment.

But now, they have competition from DOS itself. The new HIMEM.SYS included with 5.0 does more than simply serve Windows; it provides the real magic behind one of 5.0's most eye-catching features.

Is There Really 614K Free?

I just ran CHKDSK, and it told me that, despite having loaded a pile of memory-hungry device drivers and TSRs, I have 614K of my 640K free. Under DOS 3.3, that number would've been somewhere around 520K; under 4.01, it would be about 508K.

HIMEM, in concert with a new CONFIG.SYS command DOS=HIGH, actually loads as much as 64K of DOS into your computer's extended memory! Another 5.0 program, EMM386.EXE, allows you to load device drivers and TSRs above 640K, just like QEMM and 386MAX, and again, it works without a hitch with Windows.

Once you get a copy of 5.0, don't miss out on these memory benefits. You'll need to focus or the HIMEM.SYS and EMM386.EXE device drivers, the new DOS=HIGH,UMB command, the DEVICEHIGH CONFIG.SYS command, and the LOADHIGH AUTOEXEC.BAT command.

You'll have to noodle around with these a bit to make them work well, but it's worth the time. One final caution: In order to load DOS above the 640K addresses, you need an 80286 or better computer; to load device drivers and TSRs above 640K, you need an 80386 or better.

A Kinder, Gentler File System

You've done it. I've done it. Everyone's done it at some point or another: accidentally erased a file. If you're like millions of PC users, you've gone out and purchased The Norton Utilities, PC Tools, or The Mace Utilities. But 5.0 now includes the utilities UNDELETE, UNFORMAT, and MIRROR from Central Point Software's PC Tools Deluxe. UNDELETE reverses a file erasure--within limits. If you wait too long between when you've erased the file and when you try to undelete it, it may no longer be recoverable.

How does UNDELETE work this minor miracle? Simple. When DOS erases a file, it doesn't go to the actual trouble of overwriting the area on disk where the file resides. Instead, it just marks that area as usable for creating new files.

As long as you don't create any new files, there's no demand to actually utilize this available area. Create a new file, however, and there's the chance that your "erased" file will actually be irrevocably overwritten. UNDELETE sniffs out the waiting-to-be-overwritten file and reconstructs its old directory entry.

You can make life easier for UNDELETE, however, with another of the Central Point tools now in 5.0: MIRROR. MIRROR makes a copy of your system's table of contents--two areas you may have heard of, called the File Allocation Table (FAT) and the root directory.

Both UNDELETE and UNFORMAT use this copy as a starting point when reconstructing files after damage or erasure. The MIRROR backup isn't essential, but it greatly increases your chances of data recovery. And running it regularly is painless--just include it in your AUTOEXEC.BAT.

The third command of this group is the most amazing: UNFORMAT. Accidentally format a floppy disk or a hard disk, and in a twinkling you can undo the damage. This seems to violate the laws of physics, but again, there's no real magic involved. It's already been said that erasure operations don't actually overwrite files. Instead they tell DOS to forget that the files exist and treat the areas in which they reside as available. As it turns out, the FORMAT command just does the same thing on a grand scale.

UNFORMAT reconstructs the FAT and root directory, effectively nullifying the accidental FORMAT operation--again, this only works if you run UNFORMAT before you create any new files.

Along the lines of data recovery, there are two minor revisions of old DOS programs that are worth mentioning. FORMAT itself is smarter and can now format a disk in just 16 seconds, provided that the disk has already been formatted at some time in the past.

And SYS, the DOS utility that makes disks or hard drives bootable, used to be very picky about which disks it would work with. Its criteria for bootability were so stringent that it was nearly useless.

SYS's limitations really showed when trying to upgrade the DOS on your hard disk. More than once, I gave up trying to get SYS to play ball and just reformatted the disk to get the new DOS on the hard disk.

SYS is now much more accommodating. So much so, in fact, that it seems amenable to making any disk bootable, so long as there's about 85K of free space on the disk for the system files.

The UNDELETE and UNFORMAT programs, and others like them, have certainly been available through third parties for years. But it's nice to finally see them included with DOS. These tools are too good for just power users to know about. And the fact that SYS is finally useful (after a mere ten years) is quite welcome.

The Old Shell Game

More and more PC users prefer a program-launching, file-managing shell program to the arid charms of the C prompt, so word of DOS 4.01's shell program was greeted enthusiastically in the user community--at least until the community actually saw the shell.

You could say that the DOS 4.01 shell was to shells what EDLIN is to editors. DOS 5.0's DOSSHELL improves on the previous shell to a point where it's actually not bad, as shells go. Even veteran command line jocks may find a use for the shell's newest feature--task switching.

With task switching, any computer, even an XT, can load multiple programs and switch among them. Now, be sure to read that correctly. This isn't full-fledged multitasking. Load 1-2-3 and WordPerfect, and only one of them is actually running at any time--the program that you're working with.

But when you want to switch from 1-2-3 to WordPerfect, you don't need to exit 1-2-3 and start WordPerfect. Rather, you just type Alt-Esc, a key combination familiar to Windows users.

The main benefit is quick switches from one program to another, which could be quite a welcome benefit for a user with an older 8088-based system or someone who doesn't want to have to fool with Windows just to load multiple programs.

Each DOS session, by the way, gets 582K of RAM (on my system, at least)--not bad for a task switcher that comes free with the operating system.

Other than task switching, the shell has the usual shell features--mouse support for selecting files for copying and deleting, a visual representation of your disk's tree structure, and point-and-click program launching.

There are a couple of little extras, too: a 50-line screen mode and the answer to an old DOS question, How do I rename a directory? The customary way to rename a directory has been to create a new one with the desired name, copy the files to the new directory, and erase the old one. But with the DOS shell, you just click on the directory and select Rename under the File menu.

Teaching an Old DOS New Tricks

Finally, there's a group of items for which 5.0's designers can be justly proud. DOS 5.0 eradicates bugs (some ancient, some arising as recently as DOS 4.01), and it adds many long-awaited features.

Perhaps the most significant of these is much smoother support for large drives. DOS 4.01 supported drives larger than 32 MB--that was almost its sole saving grace--but it had a catch. In addition to the extra 10K of RAM that DOS 4.01 needed, you also had to load SHARE, a memory-resident program that burned up a few more K all by itself.

Setting up drives is a bit easier with the new FDISK. FDISK, for those who've avoided it, is one of the programs that you (or someone) must run when setting up a new hard disk.

Part of the setup process divides a hard drive into sections used by different operating systems--some for DOS and some for UNIX, for example. Most of us give 100 percent of the disk to DOS, but whoever sets up the disk must still make the explicit step of allocating the entire disk to DOS. DOS is not the primary partition by default.

Under previous versions of DOS, a setup person occasionally ran into a blockade. If there's already a partition from an operating system other than DOS (such as UNIX), FDISK couldn't delete it. This put installers in a difficult position if they didn't have the FDISK for the originating operating system. Only the UNIX FDISK could delete a UNIX-created partition. With 5.0's FDISK, however, you can now delete any kind of partition.

Since DOS 2.0, CHKDSK has done an odd thing when it encounters a disk problem called lost clusters. It tells you that you've got lost clusters--a relatively minor problem indicating some confusion in DOS's disk housekeeping--and offers to fix them. You give it the go-ahead, but it doesn't actually fix the problem.

Then you look more closely at the screen. Before it told you about the lost clusters, it warned you that the /F option wasn't activated, so changes would not be written to disk. What it was trying to tell you was that something was wrong, but that CHKDSK wasn't started with the /F option and that CHKDSK isn't allowed to make any changes to the disk, even much-needed fixes, without the /F option.

That doesn't keep CHKDSK, however, from leading you to believe that it is going to do something useful with the next few lines. It has confused more than one user, but no longer. Now CHKDSK is much more direct, telling you that you have a problem and that you must rerun CHKDSK with the /F option in order for it to fix the problem.

EDIT, DIR, and More

A few paragraphs back, I did a little left-handed EDLIN bashing. EDLIN's still around--for the purists--but now there's EDIT, a fairly complete full-screen text editor. It supports the mouse and has search and block operations, word-wrap, and printing--all supported by a pull-down menu system. It's easy to use, it boasts good help, and it's fast.

Ever wanted to sort the output from a DIR command? The new DIR command can sort files by size, extension, name, or date of creation. When cleaning out a directory to make space, you can sort the files by size (DIR /OS) so that you can figure out which files will yield the most space once deleted.

You can finally display hidden files (DIR /AH), or for that matter, you can display only those files that have their archive bits set (DIR /AA)--that is, files that haven't been backed up yet. And now there's a feature wherein DIR will search more than just the current directory. Can't remember where you put RESUME? It's easy to find; DIR \ RESUME /S/B does the trick.

And once you've decided on the DIR switches you'd like to use, instead of typing them each time you issue the DIR command, you can set an environment variable. For example, to always sort on filename, you'd put SET DIRCMD=/ON in your AUTOEXEC.BAT.

Now DIR not only shows you how much free space is on the disk but also computes the total amount of space taken by the files whose names it has just shown you. For example, type DIR *.BAT and it will, as always, show you all the files with the BAT extension, but it will also tell you how much space is taken up in total by those files.

And once you've found all of those BAT files, perhaps you'd like to erase some, but not all, of them. Just type ERASE *.BAT /P. The /P means pause and verify for each file. One by one, it examines all of the files, asking if that file should be erased.

Of course, having all these new options means you may miskey now and then, which makes yet another new command, DOSKEY, all the more useful. DOSKEY remembers your last 20 or so commands. Using the up- and down-arrow keys, you can recall a previous command, edit it, and reissue it, saving tons of keystrokes.

You can even write macros and assign them to keys, the way you do with 1-2-3 and other applications. There have been public domain versions of this utility around for years, but it's nice to see it's finally part of DOS.

If you've cursed DOS's BASIC interpreter, either BASICA or GW-BASIC depending on your DOS version, DOS 5.0 has a surprise for you. The new DOS comes with a reduced-function version of Microsoft's QuickBASIC compiler. It even ships with a few sample programs that are a bit more interesting than the old mortgage calculator.

Space is running out, so let's see what's left. The ATTRIB command can now modify hidden and system attributes, in addition to the archive and read-only bits, which it could modify before.

MODE CO80,50 shows a 50-line screen on VGA; there's a 43-line mode for EGA. MODE will also speed up your keyboard.

And all these neat new features cried out for another new feature: built-in help. Can't remember the new syntax for DIR? No problem. Just type DIR/?, and you'll get a complete listing of the options and syntax for the command.

So there you have it. Not only is MSDOS 5.0 a stable replacement for its older brother 4.01, but it reduces the need for file recovery tools like The Norton Utilities (around $100), task switchers like Software Carousel (around $80), 386 memory managers (around $100), hobby-level BASIC compilers (around $70), and full-screen text editors ($50 to $400). Not a bad deal. I'd say DOS 5.0 is the software bargain of the year.