Way back in 1984, a little company with the ambitious name of Borland International wrote a program called Sidekick. When early PC users discovered it, they thought they'd found computer heaven.

Until '84, Borland stayed in business by writing and selling what became the world's most-used programming language, Turbo Pascal. In those days, most techy programmers who tried to write software for non-techy consumers flubbed it. But Borland's programmers were like the sorcerer's apprentice. There are 3 million bought-and-paid-for copies of Sidekick in existence.At a time when the IBM world was still a tangle of incompatible compatibles, Sidekick gave owners something practical to do with their sluggish, simple-minded PCs. It had a calculator, a Rolodex-type filer and a telephone auto-dialer so smart it could pick out a phone number from a page of ordinary typing.

And all these tricks were pop-ups. Hit the appropriate key combination and the utility you wanted would jump up, take over part of a computer screen, do its job and disappear.

Recently, a more confident Borland dropped the International from its U.S. name. Then it presented us with Sidekick 2.0.

The very number of this version is significant. Going seven years with only one meaningful upgrade (to fuller-featured Sidekick Plus) must set some kind of PC world record.

Much of Sidekick is still the same, like the notepad that pops up from any program. It's useful for taking notes during a disrupting phone call. We use it for reminders that pop into our heads when we're neck-deep in a race to beat a deadline.

There's also a little-changed cut-and-paste utility. From inside your word processing program, you can find a phone book entry and copy it into a letter.

Many of Sidekick's changes simply reflect seven years of maturing.

The pop-up calculator is now as capable as sophisticated scientific pocket calculators made by Hewlett-Packard and Texas Instruments.

Sidekick now runs on networks so that an officeful of people can use a common computerized name-and-address file. At the same time, it can store personal card files other network users can't peek at. It has a scheduling system networked people can share, plus private personal calendars for each computer user.

You can print address books from Sidekick's files. It supports an impressive list of printers, including lasers.

There's a clever new reconciliation feature. That's for people who run the program at home, at the office and maybe even on the road. It compares two phone books or calendars and automatically copies entries to update the older file.

You can transfer data between Sidekick and Borland's full-fledged Paradox database. But this utility isn't as flexible as we'd like. We wish the program could import data files from other makers' databases. Some of our friends would loveto move their phone directories into Sidekick's pop-up form.

We also wish Borland would let us add to or change the kind of data the phone book stores. It's not nearly as flexible as most people need it to be.

Sidekick now takes advantage of expanded RAM. If your computer has any, Sidekick needs little of your precious 640K base memory to stay ready for action.

Most programmers seem convinced that mousing is the way to go. So naturally, you can now mouse around in Sidekick's screens. Right now 2.0 is on sale for $70. Its usual price is $100. Phone Borland at 800-331-0877 for your nearest dealer.

Hey, you Macintosh owners! Amaze your friends. Stump your enemies. Overcome the frustration of not being able to make IBMs and Macs talk to each other without expensive hardware and slow-moving software.

How? Load Dayna DOS Mounter into any Macintosh equipped with one of Apple's SuperDrives. The Mac will read IBM compatible files.

DOS Mounter can't make major miracles. It works only with 3.5-inch disks, either high (1.4M) or low (720K) density. When you shove the disk into the Mac's disk drive slot, its files show up on the Mac desktop exactly as if it were a Mac disk.

We use DOS Mounter to move into Macintosh files created in the IBM versions of WordPerfect and Word. To actually work on the IBM document using the Mac version of the program, we have to first put the file through the Mac version's translation utility.

But it's all so simple, the program's manual is only 34 pages including glossary. It retails for $90. If you can't find it locally, phone 800-531-0600.

Do you wish you could afford a better graphics card and monitor? For $120 retail, UltraVision may give you the sharper picture you're looking for. It forces monitors to display higher resolution type. On an older EGA system, it shows 9-by-19 dots per character instead of 8-by-14. It boosts VGA resolution a bit, too.

If you're pairing a multiscanning monitor with an older EGA graphics card, it can generate VGA quality resolution. It lets you change your display's type font and offers a 64-color palette of colors for programs to use on-screen.

We tested a lot of similar products. This one's among the easiest to install and use. It's also among the best-behaved. It doesn't hog computer time, it doesn't rebel against sharing RAM memory with other programs and doesn't insist on being the first or last one loaded. If you can't find it locally, phone 800-445-3311.