Apple Computer Inc. is selling PowerBook portable Macintosh computers at a rate of more than a million a year, which is a remarkable pace for a computer that is mostly incompatible with 90 percent of the other PCs in the world.
As might be expected from those who march to the beat of a different drummer, people who tote PowerBooks seem to take a particular pride in fine-tuning their machines.
One way to jazz up the PowerBook is to load it with the Norton Essentials for PowerBook, a $129 package produced by the Symantec Corp. of Cupertino, Calif.
The Norton Essentials is a collection of 12 utility programs that increase battery life, add some productivity features and make it relatively easy to synchronize different versions of files between a PowerBook and its desk-bound cousins.
In truth, many of the Norton Essentials utilities are not essential, but the programs are generally useful, and having them all appear under a single pop-down menu item is convenient.
The light that illuminates the PowerBook screen is the single biggest drain on battery power. The Backlight Dimmer utility dims the screen at regular intervals to save a few milliwatts here and there. You can dim the screen manually. The screen brightens when the computer is in use.
Most PowerBook users have to guess how much battery life remains.
The Battery Gauge utility gives the user a constant reference, either in minutes or in a display like a fuel gauge. It is also a constant reminder that Apple overestimated the operating life of its batteries.
Battery Saver is an important utility that lets the user determine how much time, in minutes, will pass before an inactive hard disk or processor automatically goes to sleep to conserve energy. It also determines how quickly the system will go dormant when there is no activity.
Instant Access for AppleTalk is a handy utility for office workers. AppleTalk is a built-in networking system, one of the great strengths of Macintosh technology.
But AppleTalk drains power from the PowerBook even when the portable is disconnected from the network, unless the user enters a special command to deactivate it. Instant Access makes AppleTalk connections as easy as plug in, plug out, and it stops the hidden power drain.
Some utilities, falling under the productivity category, are of dubious value, like Quick Notes, a pop-up note pad for storing information like credit-card numbers and emergency phone numbers.
An executive who works most of the time at a desktop Mac may copy a file to the PowerBook and work on it while on the road. When the traveler is back in the office, there are two versions of the same file, one current and one outdated. Syncit! finds files with the same names and copies the newer file over the older one.
This synchronizing of files is a complex issue, and Norton Essentials has some nice commands for giving the user control over which files are to be synchronized and which are not.
For more information on Norton Essentials for Macintosh, contact Symantec at (408) 253-9600.
(Peter Lewis works out of the New York Times' Austin, Texas, bureau:  328-8258.)