I was browsing through the generic aisle of our local computer store the other day when. . . . Yes, you read that right. The computer store. The generic aisle. It's the newest rage: "generic" IBM-PC clones.

In the mail-order columns of the computer magazines, and in the back corner of many computer retail stores these days, you will find a new breed of personal computer boasting "100 percent compatibility" with the IBM-PC or PC-AT and selling for prices as much as $1,000 less than the real IBM product.

These machines frequently have no label at all, or carry the store's name -- hence, the term "generic." I've seen them priced as low as $395 for the absolute bare-bones computer with no memory, disk drives or monitor (that model would total about $1,000 by the time you added the standard components); more commonly, the generics range from $1,200 to $1,700 for a standard business configuration.

These machines are available because various groups of programmers -- from Massachusetts to Taiwan -- have succeeded in producing a nearly exact duplicate of the key internal software that comes with the IBM-PC.

This crucial software element is called the IBM "ROM-BIOS." The word "BIOS" stands for "Basic Input/Output System" -- that is, the central program controlling the way you put information into your computer and get it back. This essential program is provided not on a floppy disk, like most software, but rather on a Read-Only Memory ("ROM") chip that is built into every IBM-PC.

The IBM ROM-BIOS is what makes an IBM-PC act like an IBM-PC. A BIOS chip can be copyrighted -- Apple established that rule in its landmark lawsuit against Franklin -- and IBM occasionally has brought legal action against knock-off artists who copied its chip too closely.

Clone makers like Compaq and Zenith have developed their own ROM-BIOS programs that are close to the real IBM item, but not close enough to cause legal problems.

In the past year, a whole raft of new ROM-BIOS programs has appeared. They are sufficiently similar to IBM's own BIOS to accept just about any IBM-PC software, but different enough to escape copyright infringement claims. The government of Taiwan sponsored one ROM-BIOS development effort; the South Koreans have one of their own.

The best of the lot, according to those who keep track of such things, is the ROM-BIOS, offered by an American outfit, Phoenix Software Associates of Cambridge. The Phoenix chip is the core of the highly successful Tandy and Kaypro IBM compatibles, which really come close to the mystical standard of "100 percent compatible."

With one of these ROM chips and off-the-shelf disk controller, memory and monitor circuitry, it becomes fairly simple to whip up a quick-and-dirty copy of the IBM-PC. Hence, the advent of the "generic" personal computer.

One of the most highly ballyhooed of the new clones is the Leading Edge "Model D," which is built by the Korean firm Daewoo, and can be bought for $1,400 or so for a complete system with monitor, two disk drives, 256K of RAM memory, and serial and parallel connection ports. I hear good things about this machine from users, but beware: judging from letters in the computer journals and notices on electronic bulletin boards, the Leading Edge machine appears to be incompatible with some software programs.

Should you be interested in a generic? You should indeed, if you keep certain precautions in mind while you're shopping.

First of all, you want a machine with a ROM-BIOS that really is compatible with IBM software. If you're getting the Phoenix ROM, you're probably in good shape; otherwise, be careful. See if the computer you're looking at will run the Flight Simulator program, or SideKick, or Microsoft Word -- all good tests of true compatibility.

For those components you can check -- such as keyboard, monitor, disk drives -- see whether your "generic" comes with standard brand-name equipment. You're in good shape if you're getting (among other possibilities) a Zenith or Amdek monitor, a Keytronic or Wico keyboard, and Seagate, Tandon, Shugart or Siemens disk drives.

Look closely at the configuration of the computer. You should not take a machine that does not have a serial and a parallel connection port (in some cases, you can get these by buying a single accessory board). Your "generic" probably will come with a monochrome monitor; it should have a standard "RGB" connector so later you can hook up color as well. Your computer should have enough room and power inside to add a hard disk drive at some point. Make sure the machine comes with adequate user manuals; some of the cheaper generics don't.

If you can find a clone that meets these requirements, buying "generic" can be as thrifty at the computer store as it is at the supermarket.