MS-DOS 6.0

by Alan Zisman (c) 1993. First published in Our Computer Player, March 19, 1993

New versions of DOS are eagerly awaited. Unless you've made the big jump to OS/2 or are using the competition, DR-DOS, you're dependent on this product of the Microsoft money machine if you run one of the estimated hundred million PC clones and compatibles in use around the world.

Maybe you remember the DOS 4.0 debacle. Then, late in 1988, Microsoft was to busy with (of all things) OS/2 to pay much attention to mere DOS. Instead, IBM released an inadequately tested, buggy PC-DOS v. 4.0, which was widely ignored in favor of the previous standard-bearer, DOS 3.3.

Luckily, Microsoft released that DOS was still worth doing right. For version 5, released in the summer of 1991, they conducted their largest beta-test program to date. And that product became an instant standard. As well as improving on DOS 4's features, it added a number of utilities, that had previously only been available from 3rd party companies, such as undelete and unformat, and a memory manager. As well, it was (and still is) a fairly stable, bug-free platform.

So in the first ten years of IBM-standard personal computing, there have been five major versions of DOS... one every two years, on average, with DOS 5 dating from mid-1991. That means that it's time for version 6. And the rumours started to fly. DOS 6 would be a true 32-bit operating system. It would integrate DOS and Windows into a single package.

Well, as of the time of this article, MS-DOS 6 hasn't been released, Although a March 31st release date is being widely predicted. Microsoft claims that this version has more changes to the core of the system, the 'kernal' than there were from version 4 to version 5. And the focus is on this year's buzz word, usability... making it easier for average people, not just the guys with glasses and pencil protectors.

Microsoft claims they started the process with a bunch of phone calls. Not to registered users, though, but to the general public. (They've discovered that "only power users bother to register", according to Microsoft's Alec Saunders). Out of 3000 phone calls, they found 700 PC owners, and asked what they wanted in an operating system. As a result, they have been beta-testing DOS 6 for several months, with several thousand beta-testers ranging from new users to large work-sites. Beta-testers sign a non-disclosure agreement, swearing that they will not discuss the features, or even the existence of the product they're testing. This makes sense, since features change from beta release to actual commercial product, and the beta versions are, by definition, buggier, and slower than the finished version.

Microsoft has made late beta versions available to some reviewers, and given them permission to publish. And even though I'm an authorized beta-tester, they have said that I could write this article. (Really... I have it in writing). However, you should be aware that I am looking at a late pre-release version. By the time you read this, after the expected release date, features may have changed. As well, there was no printed documentation available to me, so I could easily have missed things.

First impressions... This isn't the revolution that some rumours had speculated. It is, however, a big step up, at least in size. DOS 5 shipped on 3 low density 3 1/2" disks. This one is on 3 high density disks. It's a lot bigger. My DOS directory is up around 6 meg. When I finish beta-testing, I'll look for ways to remove a couple of megs of that, but still, that's a hefty increase.

By the way, I'm prepared to give this tendancy the force of a law... let's pompously call it Zisman's First Law of Software Obesity: "Every new software version will be twice as big as the version it replaces." In 1981, DOS v.1 took one single-sided 160k floppy. V. 2.x took two single-sided or one double-sided 360k disk. Much used 3.3 took two 360k disks, and so it's continued up to now. And at the rate we've been going, by the year 2001, DOS 10.0 will take about 96 megs of drive space. Remember, you read it here first!

The program installs similarly to DOS 5-- it creates an OLDDOS directory, giving you the power to easily restore your old set up if you want to.


The core DOS files are a little bigger, but most of the increase is in new utilities. Some of these are Microsoft designed... there's a full-screen UNDELETE that looks a lot like version 5's DOSSHELL, in addition to the old command-line version. As well, (and this is a trend for DOS 6), there's also a Windows version.

More of the added heft, though, comes from several utilities that Microsoft licensed from 3rd party sources. (Similarly, DOS 5's MIRROR, UNDELETE, and UNFORMAT commands came from CENTRAL POINT, of PC TOOLS fame). For example, there's now a virus checker, again from Central Point. And a version of SYMANTEC's NORTON BACKUP and SPEEDISK (here called, creatively, DEFRAG). Again, both the virus checker and the backup programs come in both DOS and Windows versions. You can choose to install either, both or neither version at install time. If you install the Windows versions of Backup and Anti-Virus, they're added to your File Manager menu as well as to Program Manager for easy access. They work well, but have fewer options than the full commercial products.


It seems like Microsoft's versions of DOS are always catching up with Digital Research's DR-DOS series (now owned by Novell, and with its own version 6 out for over a year). DR-DOS 6 includes a disk compressor, similar to the popular STACKER, but licensed from ADDSTOR's SUPERSTOR utility. Obviously, MS-DOS 6 would have to have this feature, too.

An unconfirmed rumour says that Microsoft licensed the core of its disk compressor from DOUBLEDISK, calling it DOUBLESPACE. They then proceeded to completely rework the code to make it better integrated with the operating system as a whole. Like the better known STACKER and SUPERSTOR, if used, it creates a large hidden file on your 'host disk', and compresses your data onto it. Its competitors use a device driver, run at boot-up, that permits you to read and write to this compressed file, on the fly. DoubleSpace, however, makes use of a new hidden DOS file, DBLSPACE.BIN, that's run before your CONFIG.SYS. You don't notice it's there... it just appears that your hard drive has a lot more room than before.

This strategy makes the disk-compression more user friendly than the earlier generation of commercial products; Stacker, for example, ends up with two versions of your set-up files. When new software changes CONFIG.SYS or AUTOEXEC.BAT, Stacker has to stop the bott-up process to adjust things. Since DoubleSpace is loaded as one of the initial DOS files, these sorts of changes don't affect it. As well, since DBLSPACE.BIN is a hidden system file, it can't be deleted accidently.

Since DoubleSpace is being included as a basic feature of DOS, Microsoft has published the specifications for it, calling it the MS Real-time Compression Interface -- MCRI) so that 3rd party utility programmers can work with it, making sure it will be compatible with upcoming utilities. By making its compression part of the operating kernal, Microsoft is setting it up to be a new standard. Users can even convert existing Stacker or SuperStor partitions to DoubleSpace partitions. (Meanwhile, the makers of Stacker, have filed suit against Microsoft.)

DOUBLESPACE has some nice features, including some that I haven't seen (at least in STACKER v.2 or SUPERSTOR v.2). For example, you can make your compressed partitions larger or smaller, in real time. The new size takes effect immediately, without needing a re-boot. While on older XTs and slower 286s, there will be a noticeable speed penalty using disk compression (with DOUBLESPACE or its commercial alternatives), on more recent computers, there should be no loss of performance, and may even be a small speed increase. File compression ratios vary depending on the type of files compressed; already compressed files like  ZIPs or GIF graphics will show little if any improvement, while other file types may compress as much as 40 to 1. I got compression ratios that were about the same as with competing products on the two partitions that I compressed.

One feature of the commercial products currently missing in DoubleSpace: while you can compress floppies, they can't be read on machines that don't have DoubleSpace installed. Both Stacker and Superstor manage to let their compressed floppies be used on any computer, whether their products are present or not.

A few warnings if you use this feature (and this is also true for the commercial equivalents):
-- For the DOS 6 DOUBLESPACE partitions, you're best off to use the DEFRAG utility provided. (Similarly, STACKER, SUPERSTOR, et al provide their own equivalents). While other utilities such as Norton's SpeedDisk will defragment a compressed drive, it won't be able to compact it, closing up the unused spaces. DEFRAG automatically switches to DOUBLESPACE to compact the compressed partition.
-- Don't try to make a Windows permanent swap file on a compressed partition, from DOS 6 or from the commercial alternatives. If DOUBLESPACE finds a permanent swap file when it is installed, it will automatically make sure it is placed in the un-compressed part of your drive.
-- Currently, DoubleSpace partitions are not supported by the next generation operating systems: OS/2 or even Microsoft's current NT beta versions. (The same is true of Stacker and SuperStor). Don't count on disk compression as a way to get enough free drive space to try out one of these large operating systems.
-- All of these programs are very safe, and have been tested widely. Accidents do happen, however, so for your own peace of mind, have a recent backup on hand before installing. Really.

While DOS 5 included the ability to load device drivers and TSRs into high memory on a 386 or better, the process had to be done by hand-editing the CONFIG.SYS and AUTOEXEC.BAT files. DOS 6 automates that, with a MEMMAKER utility, adding a feature that commercial utilities like QEMM and 386MAX have had for some time. It did me little good, however. I had followed the instructions in the DOS 5 manual to optimize my memory, and with DOS 6 and MEMMAKER, I got... (drum roll please) exactly the same amount free. On the second machine I tested, however, MEMMAKER did free up a reasonable amount of memory. If you have been (understandably) hesitant to muck about with your setup by hand, this will get the job done for you.


There are newer versions of HIMEM.SYS, EMM386.EXE, and SMARTDRV.EXE to replace the DOS 5 versions. The new EMM386 will share its expanded memory pool with other applications needing the memory. These new versions are all DoubleSpace aware, however, which may let Smartdrv hold more data in the same sized cache. (There is, also, a cute SMARTMON... a Windows utility that shows how well SMARTDRV is working) Like the Windows 3.1 version, SMARTDRV is much improved over the DOS 5 version. If you're already using QEMM or 386MAX, there may not be much reason to switch to DOS 6's equivalents.

DOS 6 does help you relate to some newer technology. The MSCDEX driver for CD-ROMs and multi-media is included.

There are a few new command line utilities... some of my favorites include:
-- DELTREE. This lets you remove a whole 'bough' of your directory tree, including contents, all in one action. Use with care!
-- MOVE. At last. Copy and delete the source.
-- POWER. For portable computer users, to conserve battery life.

As well, there are lots of new switches and features in the old standby commands. DIR /C shows you compression ratios, for example. MEM /P pauses at each page (about time!). There are lots more, including many that I haven't had the opportunity to find yet. As with DOS 5, typing the command, followed by /? will get you a brief explanation of the command, as well as a list of switches, along with their meaning.

But while the DOS 5 HELP command simply gave you that same explanation, the DOS 6 HELP is much more powerful. Here, you get a real help system, patterned on the WINDOWS HELP function. You can search for related information,  or browse an index. You really can leave the manual in the box, most of the time.

And along with the ease-of-use features, there's finally something for the hackers-at-heart as well. For those of us who find ourselves forever tinkering with our computer's setup, DOS 6 has some nice features. When it starts to boot up, you'll see "Starting MS-DOS" on screen for a few seconds. If you press F5 during that time, you'll get a clean boot. Your CONFIG.SYS and AUTOEXEC.BAT will simply be ignored. Pressing F8 steps you through your CONFIG.SYS one line at a time... you're prompted to load that line or not. You're also asked whether to run your AUTOEXEC.BAT. Chose YES, and the whole thing runs.

As well, the list of CONFIG.SYS commands has been expanded to let you include multiple configuration setups, with the ability to choose one from a menu at boot time. Similarly, a new command, CHOICE, lets you choose options from your AUTOEXEC.BAT, interactively. If you've needed multiple configurations so that you could either run your network drivers, or WINDOWS, but not both, here's a way to simplify the process.

Don't hold your breath, but in a recent interview, Bill Gates dropped some hints on what to look for with DOS 7, currently under development. The NEXT generation promises even more 386-or-better functions, and on those machines will move everything to protected mode, improve the file system, and even support real filenames... no more 8-letter mysteries. Gates suggests that DOS 7 will be merged with the next version of Windows-for-DOS (not Windows-NT), so that there'll be a single product:
DOS 7/Windows.


In the meantime, should you upgrade? If you have an older, limited system, with a small hard drive, the benefits may not warrant the increased disk space. As well, if you already have a 3rd party disk compressor, virus checker, backup program, and memory manager, you may find much of DOS's bulk unneccesary. DOS 6 is not a revolutionary change in the way your computer works. While I  like it, despite the improved ease of using memory management and help (among other improvements), it doesn't feel like as big an improvement over DOS 5 as that upgrade was over DOS 3.3 or 4. (Microsoft may hate me for saying it, but DOS 5.1, anyone? After all, 5.1 has been a lucky number for Word Perfect).

In essence, it includes some nice improvements  along with a group of utilities derived from other companies, and added hooks to Windows 3.1 and multi-media. The interactive boot capability is a particularly nice feature. Some of us, however, NEED to have the latest version of everything. For us, it's no question. When DOS 6 is officially released, we'll be lining up at our nearest software store to get it.

(Note from the year 2003): The above article was originally published in 1993, as a review. A decade and more later, I've gotten a series of emails from DOS fans hoping that I could sell them a copy of this software or direct them to a place where it is still available. While I have reviewed software since 1991, I am not a vendor of r any products. I suggest to everyone looking for copies of older software to check at eBay or at you check on my Files webpages, you'll find links to a number of (mostly freeware) downloadable software, some of which may be good replacements for older programs.
-- AZ (September 15, 2003)

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Alan Zisman is a Vancouver educator, writer, and computer specialist. He can be reached at E-mail Alan