Classic Computer Magazine Archive COMPUTE! ISSUE 162 / MARCH 1994 / PAGE 18

Old DOS, new tricks. (IntroDOS)(Microsoft's DOS 6.2) (Software Review) (Evaluation) (Column)
by Tony Roberts

Microsoft has taken the wraps off DOS 6.2, an operating system miniupgrade that's widely regarded as a bug fix for DoubleSpace, the disk-doubling utility introduced in DOS 6.0.

Although correcting DoubleSpace problems may have been the driving force behind this upgrade, DOS 6.2 includes a handful of features that will be of interest to all users--even those who don't use DoubleSpace.

First, however, let's see what changes have come to DoubleSpace.

The program how includes what's called DoubleGuard, a checksum-based system that identifies corruption in DoubleSpace memory buffers before data is written to disk. If this verification fails, the system is shut down to limit further data corruption.

DoubleGuard slows system performance slightly, but it can be turned off if you wish to run your system without it.

Other new DoubleSpace features include Uncompress and Automount.

Uncompress can return compressed drives to normal and then uninstall DoubleSpace.

Automount allows the system to recognize compressed floppy disks and other compressed removable media automatically. The new DoubleSpace includes clearer error messages, and its footprint in memory has even been reduced by a few K.

In a statement that hints at some of the rough edges users have encountered on DoubleSpace in version 6.0, Brad Silverberg, a Microsoft vice president, describes the enhanced safety features in version 6.2 as "the software equivalent of passenger-side air bags and antilock brakes to make disk compression as easy and safe as possible."

A new general-use feature of DOS 6.2 is ScanDisk, a disk repair tool. This program works with both compressed and uncompressed drives to diagnose and correct disk errors such as lost clusters and cross-linked files.

ScanDisk can also perform a surface analysis of your media and can lock out any unreliable sectors. ScanDisk's capabilities go well beyond those of the old standby Chksk, rendering that familiar program virtually obsolete.

The SMARTDrive disk cache utility also has been spruced up in this upgrade, providing additional functionality as well as safety. Most notably, the program now is able to cache CD-ROM drives. In addition, SMARTDrive now has write caching disabled by default. However, if write caching is enabled by the user, SMARTDrive will flush its cache to disk before returning the user to the C prompt, preventing the loss of data that occurs when the computer is turned off before the cache is fully flushed to disk.

DOS 6.2 improves on its predecessor by allowing interactive execution of AUTOEXEC. BAT as well as CONFIG. SYS statements. This feature makes it easy to debug a troublesome startup routine. Another startup improvement allows DoubleSpace users to boot without loading DoubleSpace by pressing Ctrl-F5. Also at startup, the high-memory manager, HIMEM.SYS, now performs a more rigorous test of extended memory than occurs in most Power On Self Test routines.

Another noteworthy addition to DOS 6.2 is single-pass disk copying. DOS now makes use of available hard disk space to permit floppy-to-floppy copies without requiring multiple disk swaps. And speaking of copying, the Copy, Move, and Xcopy commands will now warm a user if they are about to overwrite a file of the same name. Ingeniously, this feature is only employed with commands that are issued from the DOS prompt. Copy, Move, and Xcopy commands executed from batch files will proceed as before, without warning about overwrites. So your existing batch files will run as before, but when you use these commands at the command line, you'll be prompted before data is overwritten.

Other programs enhanced in DOS 6.2 include Defrag, which now is able to defragment disks that hold as many as 20,000 files; Windows Undelete, which no longer allows users to enter invalid filenames; and Dir, Mem, Chkdsk, and Format, which now display numbers of four or more digits with commas.

If you're a current user of DOS 6.0, you can get the Step Up version of DOS 6.2 from software resellers for $9.95 or by downloading the upgrade files from the Microsoft area on CompuServe, GEnie, or America Online. Or you can connect to the Microsoft Download Library at (206) 936-6735. You must have DOS 6.0 running on your system to use the DOS 6.2 Step Up.

Users of earlier versions of DOS can purchase DOS 6.2 from software retailers for a suggested retail price of $77.95. Also available is DOS 6.2 Upgrade for Dummies, which includes a copy of Dan Gookin's popular DOS for Dummies. The suggested price for that version is also $77.95.

More than a bug fix, less than a new operating system, DOS 6.2 offers plenty of good reasons to move up, whether you're running 6.0, 5.0, or something still earlier.