Disk Compression Nets More for Less

The lure of so-called disk compression software is strong: By simply installing one more program on your jam-packed hard disk, you can double its storage capacity.

In this era of graphics-oriented Windows programs that eat up to five, 10 or more megabytes of hard disk storage, your computer can quickly run out of space. An obvious solution is to buy a second hard drive. But even though prices have come down, hard disks still cost several hundred dollars or more.

For $139, though, you can buy SuperStor 2.0, the latest version of so-called disk compression software from Addstor of Menlo Park, Calif., (800) 732-3133.

Compression is a reliable process that is sort of like shorthand for computer files. The software analyzes program and data files and then stores them in a more compact form.

On my computer, before installing SuperStor, there was space left for only about 15 megabytes of files on my 145-megabyte hard drive. After installing SuperStor, I had room for 130 megabytes. The program increased the effective size of my hard disk by about 90%.

When you need to run a program or use a data file that has been compressed, SuperStor automatically decompresses it, restoring the file exactly to its original form.

The new version of SuperStor fixes one of the problems that has plagued compression software. Files that are compressed on floppy disks typically cannot be copied from one computer to another unless both computers have the same compression software.

In version 2.0, SuperStor adds a feature called Universal Data Exchange that automatically decompresses floppy disk files when they are transferred to computers that don’t have SuperStor.

To do its work, SuperStor has to take some of the computer’s operating memory, or RAM, which stands for random access memory. It needs 47 kilobytes, but if you use one of several available memory management systems, that figure can be cut to just 17 kilobytes. Most IBM and compatible machines have 640 kilobytes of memory available for running programs.

But as meager as that memory requirement may sound, it still might be too much for your system, as it was for mine. And that’s when things get difficult.

Installing SuperStor is a one-way procedure. Once you have compressed all the files on your hard disk, the program cannot decompress all of them and restore your disk to its original condition if you later decide that it doesn’t suit your needs.

Unfortunately, that fact can only be inferred from careful reading of the instruction manual. It is not explicitly stated. You are, however, admonished to make a complete backup of your files before installing SuperStor. If you don’t, you could lose all of the contents of your hard disk if there is a power failure while you are installing SuperStor.

Even though you cannot decompress a compressed disk, you can return to the way things were by copying your files onto diskettes or tape, reformatting the hard disk with DOS and copying the files back from floppies or tape to the newly formatted hard disk.

My problem resulted from too many other memory-gobbling accessories and programs on my computer, which prevented SuperStor’s memory-management alternatives from providing any relief. The 47 kilobytes that it required were the proverbial straw breaking the camel’s back, and I no longer had enough memory left to run some of my software.

Since I had recklessly ignored the instruction to back up my files before installing SuperStor, I had to do so afterward. I used a tape-drive system that was not affected by SuperStor, so the files copied to it were automatically converted into their normal, uncompressed form.

I also tested the standard DOS Backup and Restore programs to copy some compressed files to diskettes and place them on another computer not equipped with SuperStor. It worked perfectly.

There are other alternatives to making more space available on crowded hard disks. One is to use software such as PKZIP or LHARC, which compress individual files into about half their normal size. The process is called “archiving,” and it lets you compress seldom-used files to reduce the storage load on your hard disk.

I recommend XtreeGold 2.5, a $149 disk management program from Xtree Co., San Luis Obispo, Calif., (805) 541-0604, which has “archiving” programs built in.