Using a computer to make a single label or address an envelope is usually more trouble than it is worth. Until recently, I kept a typewriter near my desk for envelopes and labels. But that old typewriter has finally been exiled to the closet now that I have a Smart Label Printer from Seiko Instruments.

The printer, which works with both IBM compatible PCs and the Apple Macintosh and comes with software, is optimized to create and print one label at a time. You can also print several copies of a single label or use the mail list option to print multiple labels from a data file on your disk.

The one-pound machine plugs into a PC communications port or to either the printer or modem port of a Mac. Since all Macs and most PCs also are equipped with printer ports, the device doesn't interfere with your regular printer.

When you want to create a label, you simply load in the software and type in the text. The software works as a memory-resident program on the PC or as a desk accessory on the Mac so that, on either machine, it can pop up even while you're using another program.

After the program is on screen you can type several lines of text. You can also capture a name and address line directly from your word processing software or other program. So, if you have the name and address typed into your letter, you can easily transfer it to the Smart Label Printer's software. The software automatically searches through your document to locate what it considers to be a valid name and address. It also can print bar codes.

The machine comes with one roll of gummed pressure-sensitive thermal labels. Additional labels (130 per roll) are $9.95 for a pack of two rolls. The unit has a suggested retail price of $249.95. It and additional labels can be ordered from CP Plus Inc. at (800) 274-4277. Other dealers may offer the labels at reduced prices.

Seiko Instruments can be reached at (800) 888-0817 or (408) 922-5900. Fax: (408) 922-5835.

Sometimes you want to print more than one label at a time. Although it can be done with the little Seiko printer, it's a very slow process and not at all cost effective. Chances are that you already have a printer that can do the job. What you need are special printer labels and, possibly, some software to make the job easier.

The type of label stock depends on whether you're using a laser printer or a regular "impact printer" such as a dot matrix or daisy wheel. If you're using a laser printer, you need label stock that comes on 8 1/2-by-11-inch sheets, specially designed to run through the laser printer. Avery International Corp. makes label stock for both laser and dot matrix printers in a wide variety of sizes and styles.

You can print labels using just about any database or word processing software, but it's not always easy. Getting the labels properly aligned with the software can be tricky. Some programs come with predesigned templates for the popular label sizes, but I've never had much luck getting them to work just right. If you do decide to print labels with your word processing, spreadsheet or database program, it's a good idea to experiment with plain paper before wasting expensive label stock.

In addition to labels, Avery also offers software programs for both the IBM PC and Mac. It publishes two LabelPro products for IBM compatibles. One is designed for laser printers and the other for dot matrix printers. The Mac version works with both the Apple LaserWriter and ImageWriter (dot matrix) printers plus the Hewlett Packard DeskJet.

All of the versions allow you to integrate text and graphics on your labels. The program comes with a selection of "clip art," but also works with standard graphic files, making it possible, for example, to include a company logo that has been scanned into the computer.

Although they accomplish the same results, the Mac and PC versions are quite different. The Mac version takes advantage of that machine's graphical user interface to provide you with a "what you see is what you get" environment for designing your labels. The Mac version lets you to paste in graphic images from just about any Macintosh graphics program and gives you access to all text styles available on your Mac.

The IBM PC version lets you place graphics in pre-specified locations and comes with two type styles that can be printed in any size from 6 to 96 points. The dot matrix version offers three fonts plus your printer's resident fonts. It also prints colors on color printers.

The Avery LabelPro software has a suggested retail price of $99.95, but I've seen it on sale for a lot less. Avery can be reached at (818) 915-3851.

Readers' comments are welcomed, but the author cannot respond individually to letters. Write to Lawrence J. Magid, P.O. Box 620477, Woodside, Calif. 94062, or contact the L. Magid account on the MCI electronic mail system.