While attending MacWorld in San Francisco last fall, I walked by what appeared to be a large, framed picture hanging on a wall.

The black-and-white photo of a woman in the frame is what initially caught my attention. But anyone who has attended a large trade show knows there are thousands of other things that vie for your attention.

However, as I started to turn away, the image in the frame rolled up and was replaced by huge, solid-black block letters that screamed out an advertisement. It was so unexpected, I did a double take. What I had seen was a novel device from Applied Resources Inc. called the Information Station.

The Information Station presents clear, sharp black-and-white text, illustrations and photos on a 24-by-34-inch surface. Because the unit is only 3.2 inches thick, you can easily hang it on a wall or stand it on an easel.

Just as a printer prints on paper, the Information Station prints images on a continuous plastic loop using the same toner-based electrophotographic technology found in copying machines and laser printers. But unlike these devices, which use up the toner after 1,000 or so copies, the Information Station reuses the toner over and over again.

As a new image is being displayed, the old image is being erased from the loop. The toner is then reused in the next image. All of this takes place in less than nine seconds.

Although nothing is consumed, Applied Resources recommends that the toner and film loop be replaced after the unit generates 50,000 images. Replacement costs $500 -- about a penny per image.

Versions are available for the Apple Macintosh and IBM PC and compatibles. Each has software that allows you to display images in a slide-show fashion.

Images from fax machines, scanners, modems and other serial devices can be displayed as well. Uses range from business presentations to advertising.

The Information Station sells for between $10,000 and $15,000, depending on which accessories you buy.

(Applied Resources Inc., 1-800-826-7963 or 913-469-9191.)

I'm away from the office computer for days at a time, so I need an inexpensive way to do my word-processing and spreadsheet work. Is there an alternative to the laptop computer, which for me is too bulky and expensive?

Portable computers usually fall into one of these four classes:

Transportables weigh more than 15 pounds and look like small suitcases.

Laptops weigh between six and 10 pounds and look like small attache cases.

Notebooks weigh about four pounds, are usually one-inch thick and look similar to what they are named after.

Palm-tops are the smallest of all, weighing about a pound, and are smaller than a videocassette.

The first three classes come with all sorts of built-in options such as hard drives for storage and modems to send data over the phone. Prices range from about $1,500 to $10,000.

Because you indicated you were looking for an inexpensive model, you should consider Atari's Portfolio, which is a palm-top, at a suggested list price of $399.95.

Using MS-DOS 2.11 compatible commands, Portfolio's built-in computer applications include a Lotus 1-2-3 file, compatible spreadsheet and a simple word processor.

An appointment calendar with reminder alarms, a calculator and an address directory with audio phone dialer are built in as well.

Credit card-sized memory cards, available in 32k ($99.95), 64k ($129.95) or 128k ($199.95), are used instead of magnetic disks to store your data. Since one "k" holds 1,024 characters (a letter, number or punctuation mark is one character), the 128k card can hold up to 50 pages of standard text.

Other available cards are DOS Utilities ($89.95), which is a collection of housekeeping programs that make life on the Portfolio easier, and the Finance card ($89.95).

The Finance card performs many financial, business and statistical calculations, including compound interest on loans and savings, nominal annual percentage rates, commission and sales tax, break-even analysis and forecasting. The results can be applied to graphs or entered into Portfolio's spreadsheet and calculator.

Portfolio comes with a 63-key IBM PC software compatible keyboard and a liquid crystal display screen that displays a 40-column-by-8-line character mode and a graphics mode. Three size AA alkaline batteries provide four to eight weeks of average use.

Other accessories include serial ($79.95) and parallel ($49.95) interfaces that connect Portfolio to printers, modems or other computers. Portfolio can send your data to, or receive it from, almost any type of computer, from Macintosh to IBM clone.

For those of you with IBM PCs or compatibles, you can purchase the PC Card Drive ($99.95), whose card plugs into one of your PC's card slots. By inserting a memory card into the attached Card Drive unit that sits on your desk, data can be transferred to and from the card and your PC.

(Atari Computer Corp., 1-800-443-8020 or 408-745-2000.)

Craig Crossman is a contributing editor to several computer publications and has a degree in computer science from Florida Atlantic University.